Dreaming

Contents History of the Study of The Interpretation of Dreams The Psychology of Dreams Dreams, Psychopathology, Psychotherapy Dreaming and Psychiatric Disorders Neurobiology of Dreaming

History of the Study of Dreams R Cartwright, Rush University Medical Center, Chicago, IL, USA

ã 2013 Elsevier Inc. All rights reserved.

Glossary Imagery rehearsal therapy: A treatment program for Activation-synthesis theory: Hobson and McCarley theory the control of through practice during that dreams are initially random images that acquire waking of pleasant visual images. meaning following arousal. Incorporation: Inclusion in the report of an Atonia: Abrupt loss of muscle tone at the onset of rapid eye external stimulus. movement (REM) . Mood regulation function: Dream reports Dream: A hallucinatory experience during sleep consisting are initially negative in emotion and progressively of visual images related in a story-like structure, which are become more positive at the end of the accepted as reality at the time. night. EMs: Eye movements during a REM period, which vary in Nightmares: Strongly unpleasant dreams that speed and density. These may relate to the visual content of awaken the dreamer with full recall of the dream the dream. story.

The Early History of Laboratory Investigation of Dreams continuity of the reported dream story. REM periods were divided into those that were continuous and those that were Dreams have been a source of interest throughout human interrupted by a body movement. The dream reports from history. However, much of this literatureELSEVIER does not meet the these episodes were judged as being either a continuous narra- criteria of being a ‘study.’ This article will cover only investiga- tive or one with an abrupt change to another story. The data tions that test a hypothesis. Such studies began in the mid- analysis showed that REM periods, free of body movement, 1950s when laboratory-monitored sleep proved dreams could yield continuous dream reports while those with one or more be elicited reliably by awakening sleepers from a specific neu- body movements were associated with reports of unrelated rophysiological state known as rapid eye movement (REM) dreams. This established that REM sleep is typically free of sleep. This article will cover some highlights of the research body movements and that their presence interferes with that followed. dream continuity. This study led to the addition of a chin muscle monitor, in recognition that loss of muscle tone is a reliable signal of the onset of REM sleep and thus the likely Hypothesis: Dreams are Related to REM Sleep presence of dreaming. Characteristics Another hypothesis tested whether the reported dream is related to the type of eye movements (EMs) that precede the Early sleep studies, and more recent brain imaging work, hy- awakening. The EMs were divided into those that were large pothesized that REM sleep determines the psychological char- (high amplitude) and dense (occurring in bursts) versus those acteristics of dreams. The first such study hypothesized that that were slower and sparser. A significant association was found body movement within a REM period would disrupt the between the activity of the EMs and a dream story in which the

124 Encyclopedia of Sleep http://dx.doi.org/10.1016/B978-0-12-378610-4.00028-0 Dreaming | History of the Study of Dreams 125 dreamer was engaged in some activity. As per reports following Hypothesis: Dreams are Related to Each Other Within sparse EMs, the dreamer was passive or was ‘just observing.’ the Night Studies correlating REM characteristics and dream features waned following the publication of the Hobson and McCarley Testing the relation of dreams to each other found these were activation-synthesis theory of dream construction. These neu- not obviously similar within the night nor did all the dreams of roscientists had located the cells involved in initiating REM a night make up one continuous story. The conclusion was that sleep to be in the pons, an area at the base of the brain. They dreams are independent stories but with some elements in argued that as this excitation traveled upward through the common, and that those that were similar were not always occipital cortex, random visual images were stimulated. These found in reports from adjacent REM periods. Since in only a acquired meaning only during arousal when the higher brain few cases was the same theme expressed throughout all the areas attempt to make sense of these inherently meaningless dreams of a night, it was concluded that, at the level of the images. Later, brain imaging studies, using positron emission manifest content, dreams are not related to each other. This tomography (PET) scans and functional magnetic resonance raised the question of whether the experimental awakenings imaging (fMRI), identified patterns of brain areas that are more were disrupting a natural continuity of the dreams. Further or less active in REM sleep than in waking, or in nonrapid eye study showed the amount of time spent awake for the sleeper movement (NREM) sleep and the relation of these to the to report their dream was negatively related to the continuity known function of these brain areas. These studies added between that dream and the report from the next REM awak- specificity to the description of REM as a highly activated ening. The longer the time awake, the less the continuity was. brain state. Finding strong activity in the limbic and paralimbic Although awakenings from REM yielded a report of dream- cortex (the amygdala, hypothalamus, the anterior cingulate) ing 80% of the time, those from nonrapid eye movement supports that dreams are more likely to involve negative emo- (NREM) sleep yielded widely varied percentages of dream re- tions. The deactivation of the prefrontal cortex accounts for the ports. The highest percent was found at . More difficulty remembering dreams and the weakening of reality typically, NREM reports differed in quality from REM reports. testing (accepting the dream as if real). Dream reports collected They were described as less imagistic and more thought-like, during these imaging studies verified that dreams were being less emotional and more pleasant than the highly emotional, experienced during a specific pattern of increased and de- unpleasant reports from REM. To test whether the failure to creased brain activity in healthy persons but these varied in find continuity between dreams of the same night was because different clinical samples. This moved the the dream theme was set prior to the first REM, the next question back from being a waking afterthought to being due investigation collected samples from both NREM and REM to the particular brain areas active in the REM state. sleep, sampling all Electroencephalography (EEG) stages of sleep. Sleepers were awakened either 30 or 90 min following sleep onset by a coin toss. The coin toss was repeated following Hypothesis: Dream Images are Internally Generated each report to determine the timing of the next awakening. This resulted in 6–9 reports each night in random sequences of Early experiments attempted to test whether the images reported various sleep stages. The reports were examined for repeated in dreams could be influenced by applying a variety of external images or themes in the manifest content. Sometimes, the stimuli during an ongoing REM episode. They first used an initial report was from a NREM stage before any REM had auditory tone, a flashing light, and a spray of water, followed occurred. Repeated elements were found in different sequences by a doorbell to awaken the sleeper to report their experience. of sleep stages. Testing continuity of the sleeping mind using None of these stimuli was ‘markedly effective’ in modifying the this random awakening schedule presents a real difficulty: ongoing dream. Another study used auditory stimuli of spoken repeated elements may be present but missed if the random proper names, two of which were emotionally salient and two protocol skipped a time when reports were most connected. were neutral. The finding was that half of the dream reports In conclusion, there were nights with little or no repeated ele- showed some effect although this wasELSEVIER not by a direct inclusion ments and others when these were plentiful in both NREM and of the names but by a similarity in sound of a word in the report REM sleep. During nights when these were frequent, they were to the stimulus name (via assonance). Familiar names, their also the most vivid and memorable of the reported dream but own or those of ex-girlfriends, were more likely to have an effect were embedded into distinctly independent contexts, suggesting on the dream content than neutral names. The finding that that they were driven by intense preoccupations (possibly pre- emotional stimuli have more effect on dream content than conscious day residues), which then interfaced in sleep with those neutral in tone has been a repeated finding. ongoing unconscious (latent) dream thoughts. The conclusion To test whether the auditory stimuli had more effect on was that there is an interaction of preconscious and unconscious dreams than the visual, because the receptor organs (ears) streams of thought throughout sleep but that the methods used were open in sleep while the eyes were not, volunteers were to analyze dreams were not appropriate to identify these. tested while sleeping with their eyes taped open. Once REM was identified, an experimenter held up an object in front of the sleeper’s eyes, before they were awakened to give a dream report. Judges attempted to match these reports to the stimulus Hypothesis: Dreams Relate to the Presleep object. As they were not able do this at a rate better than Waking State chance, the conclusion was that dream images are internally generated and only on rare occasions are external stimuli re- The findings of the TV study reported above pushed the ques- sponsible for some element of a dream. tion of how dreams are constructed back still earlier to examine 126 Dreaming | History of the Study of Dreams the influence of the emotional state of the participants before interactions. On the final night, Night 5, the recall rate returned they fell asleep. It was clear that there was also a need for more to the baseline control level and the number of dreams with two subtle and more systematic methods to measure dream con- characters was significantly higher than on the control night. tent. The most comprehensive and influential of the scales In summary, the findings of an immediate increase in fail- developed were those of Hall and Van de Castle. These allowed ure to recall from REM awakenings and lack of any direct studies to compare dream reports of various groups on stan- incorporation into dreams of the arousing movie suggested dardized measures. Differences were found between the an inhibiting effect possibly related to the presleep interactions dreams of men and women, older and younger age groups, with the laboratory personnel, two attractive female techni- ethnic groups, and many clinical groups such as alcoholics and cians, with whom they had some bodily contact during the nondrinkers. Studies of the relation between the prior waking application of the electrodes. This appears to have raised psychological state and the dreams of the night began to use about having, or reporting, explicit dreams leading to both a the Hall and Van de Castle scales for standardizing the dream dampening of recall and increased number of dreams with only content and various personality tests for measuring waking one character. The conclusion was that although the sexual traits and states. The presleep emotional state of the volunteer movie produced an immediate physiological arousal response was then manipulated using stimuli chosen to be emotion in waking, it was inhibited from direct expression in sleep on invoking or bland, and reports from the following dreams Night 2. On the following Night 3, the number of symbolic were analyzed using the new content scales. One study used sexual words in the dream reports hit the highest peak. Over the two episodes of a TV series, one very violent and the other a next three nights, there was a gradual return to the baseline recall comedy. The order of these was counterbalanced on two sleep rate. The laboratory situation appeared to have a powerful inhi- nights. Reports were collected from both REM and NREM sleep biting effect on the drive aroused by watching the movie. episodes to explore the differences in the influence of these Finding that the planned effect of experimental stimuli movies on the different sleep stages, as well as the relation to often had a minimal effect and that the social context may the waking personality characteristics. The aggressive film pro- have a more powerful, unanticipated effect on dream content, duced longer and more imaginative, more vivid, and emo- there was a shift in research strategy toward more naturalistic tional REM reports than did the comedy movie. However, studies. Dreams following natural disasters, such as the 9/11 these film differences were not found between the reports terrorist attack, the holocaust, bereavement, divorce, kidnap- collected from NREM sleep. The correlation of dream charac- ping, rape, and living under missile attacks, have all been teristics and the waking personality tests showed an ‘extremely studied. The landmark study of this kind chose an inherently consistent pattern of correlations between the clinically ori- emotion arousing event, elective surgery, to study the effect on ented scales and dream-like features of the reports.’ The imag- dreams. Patients were recorded for four nights before and three inativeness of the person in waking was highly correlated with nights after surgery. Rating scales were constructed for analyz- that aspect of the dream reports. There were no significant ing the dreams including degree of recall, anxiety, and involve- direct incorporations of either film into the sleep reports. ment. The general conclusion was that the surgeries meant Why the aggressive film had a clear impact on REM reports different things to different patients. The initial dreams never but not on those from NREM and why, despite the increase in dealt with the surgery directly but as has been seen before there vivid, imaginative, emotional REM dreams after the violent were many transformations to represent this event symboli- film, were the dreams not more violent or unpleasant? The cally. Most apparent was that the dreams demonstrated the explanation offered was that the violent film had a general participant’s attempts to integrate the present stressful event effect and not a specific one, and that the general emotional into their individual adaptive strategies that had worked for arousal stimulated the viewers’ personal emotional memories them in the past. If this has a learning effect on future coping, to be displayed during REM sleep. longer follow up would be needed. To focus the waking attention to a specific drive, the next study included a physiological measure of sexual arousal dur- ing the exposure to a pornographicELSEVIER film. This study examined Hypothesis: Dreams Effect Postsleep Psychological the effects of this on the dreams of adult men over five nights of Functioning REM collections. The first night was a control to assess the baseline rate of sexual dreams. The following day, the partici- Studies of the effect of dreams on changing the waking mood pants wore a penile strain gauge to measure their response to have examined both healthy persons and those with clinical the movie shown before their second night. The dream reports diagnoses. One study of a healthy, high functioning sample were analyzed using the Hall and Van de Castle norms for the used the Profile of Mood States (POMS) test before and after frequency of common words in the dream reports of a similar sleep for two nights with REM interruptions for collecting sample of adult men. Judges first rated these words for sym- dreams on the second night. The sleepers rated the emotional bolic sexual reference, for example, balls, nuts, shaft, and foun- quality of each dream immediately following their report as tain. The judges agreed on ten words as having symbolic sexual positive/pleasant, neutral, or negative/unpleasant. The sample meaning and ten others were chosen to refer to the laboratory was divided on the presleep mood score into those who had setting. There was a marked increase in the symbolic words in little or no elevation on the Depression Mood Scale and those the dream reports over the rate expected from the norms. That who had a mild elevation of this negative mood. The Not this might represent a latent response to the sexual film was Depressed (ND) group had twice as many positive dreams as supported by a significant increase in ‘No recall’ reports on negative and the Mildly Depressed (MD) had an equal number Night 2, and an increase in number of dreams with one charac- of positive and negative dreams. To test whether dreams regulate ter, indicating a possible suppression response to two-person mood within sleep, the average ratings of dream affect in the first Dreaming | History of the Study of Dreams 127 half of the night was compared to the average of those in the Partly, this is due to recent studies of patients with brain second. The ND had more positive than negative dreams in injuries, seizure disorders, and psychosurgeries who report both halves. The MD had a high proportion of negative dreams changes in their dreaming. Solms reported almost 1000 cases in the first half-night, with a marked decrease in the last half and experiencing a cessation of dreaming following a focal fore- the opposite pattern for positive dreams; with few at the begin- brain lesion. Many of these were confirmed as ‘dreamless’ by ning of the night and a high proportion at the end of the night. the REM awakening method. In these cases, the pontine brain The conclusion that sleep generally improves morning stem was completely spared and REM sleep was intact. Further, mood was confirmed by a lower depression score following he found that dreaming can be initiated by a forebrain mech- both nights. Whether this effect is related to the intervening anism independent of the REM state in those with nocturnal dreams was supported by the finding that the affect in first seizures occurring in NREM sleep, which are experienced as dreams of the night was significantly correlated to the previous nightmares. Comparing a large sample of patients who waking mood. Even when this mood was only mildly un- reported changes in their dream experience and a healthy happy, negative dreams dominate in the first dream reports control sample, Solms identified the brain areas that had and then decrease in the second half-night. The natural se- been damaged or surgically removed and the patients’ experi- quence appears to be that the emotional state before sleep is ence of changes in their dreams, to map the structures respon- continued into sleep onset, stimulating a network of memories sible for specific characteristics of dreams, for example, the associated with similar feeling. The varied dream scenarios or presence of color or of people. This led him to conclude that ‘contexts’ appear to dissipate the negative mood, which in turn dreaming and REM sleep are controlled by different mecha- accounts for the improved morning mood in healthy persons. nisms; with REM initiated from the pons and dreaming from If this is a natural function in well-adjusted adults, do dreams the forebrain. What is common is that dreaming occurs not display dysfunctions in those not emotionally fit? only in sleep when the brain is highly activated as it is in REM but also in the transitions between waking and sleep; at sleep onset in NREM and at the end of the sleep cycle just prior to Hypothesis: Dreams Differ in Psychiatric Patients waking. This allows clinical intervention for control of night- mares, to target sleep onset. The other major conclusion from this review is that dreams The ‘naturalistic’ studies, particularly of sleep during or after are strongly influenced by the waking emotional state, which is traumatic events, brought attention to the study of nightmares. not expressed directly but in sensory images drawn from asso- These -inducing dreams lead to an interruption of sleep, an ciated memory networks. These will be displayed in a sequence awakening with full recall of the dream. These are the most of dreams that function to down-regulate negative mood. disturbing symptom of posttraumatic stress disorder (PTSD), Given these studies, it should be possible to estimate the health the most long lasting symptom and the one most difficult to of this function by collecting only two samples: the first from treat. The PTSD diagnosis includes not only distressing dreams sleep onset and the second from the end of sleep. This would but in some exact replications of the traumatic event. Treat- avoid disrupting the sleep with REM awakenings and minimize ments that train patients to control their dreams have become the laboratory effect. the behavioral treatment of choice. To test whether dreamers are capable of controlling their dreams, Imagery Rehearsal Therapy, a brief clinical program, was developed. This begins See also: by training patients to rehearse a positive image of Critical Theoretical and Practical Issues: Future of their choice during waking. Next step is to write out their Sleep Research; The Function of Sleep; Dreaming: Dreaming and nightmare but to change the ending to one they prefer. That Psychiatric Disorders; Dreams, Psychopathology, Psychotherapy; this trains nightmare control is being reported in some studies Neurobiology of Dreaming; The Interpretation of Dreams; The based on self-report. Psychology of Dreams; Instrumentation and Methodology: Dreams have also been studied in major depression since Neuroimaging and Sleep; Nocturnal Penile Tumescence; Psychiatric these patients show abnormalitiesELSEVIER of REM sleep and dream Associations of Sleep Loss/Deprivation: Changes in Affect; reports that are both brief and bland in feeling when the Personality and Psychopathic Changes depression is severe. Moderate depression is characterized by dreams with negative feelings, which fail to reduce, in fact increase, in frequency within the night. Those whose within- sleep pattern of dream affect resembles that of healthy samples, Further Reading with decreasing negative and increasing positive dreams within the night, are more likely to remit without treatment within a Cartwright R (1990) A network model of dreams. In: Bootzin RR, Kihlstrom JF, and Schacter DL (eds.) Sleep and Cognition, pp. 179–189. Washington, DC: American year. This finding has been confirmed in several studies leading Psychological Association. to the first verified function of dreams: dreaming performs a Cartwright R (1991) Dreams that work: The relation of dream incorporation to adaptation mood regulatory function. to stressful events. Dreaming 1: 3–9. Cartwright R (2005) Dreaming as a mood regulation system. In: Kryger M, Roth T, and Dement W (eds.) Principles and Practice of , 4th edn., pp. 565–572. Philadelphia, PA: Elsevier Saunders. The Future of Dream Research Cartwright R (2010) The Twenty-four Hour Mind: The Role of Sleep and Dreaming in Our Emotional Lives. New York, NY: Oxford University Press. Cartwright R, Bernick N, Borowitz G, and Kling A (1969) The effects of an erotic movie As reviewed here, studies of the last 60 years have freed dreams on the sleep and dreams of young men. Archives of General of being seen as meaningless accompaniments of REM sleep. 20: 262–271. 128 Dreaming | History of the Study of Dreams

Dement W and Kleitman N (1957) The relation of eye movement during sleep to dream Krakow B, Hollifeld M, and Schrader R (2000) A controlled study of imagery rehearsal activity: An objective method for the study of dreaming. Journal of Experimental for chronic nightmares in sexual assault survivors with PTSD: A preliminary Psychology 53: 330–346. report. Journal of Traumatic Stress 13: 589–609. Dement W and Wolpert E (1958) Relationships in the manifest content of dreams Kramer M (1993) The selective mood regulatory function of dreaming: An update occurring on the same night. The Journal of Nervous and Mental Disease and revision. In: Moffitt A, Kramer M, and Hoffman R (eds.) The Functions of 126: 568–578. Dreaming, pp. 139–195. Albany, NY: State University of New York Press. Ellman SJ and Antrobus JS (1991) The Mind in Sleep: Psychology and Lavie P and Kaminer H (1991) Dreams that poison sleep: Dreaming in holocaust Psychophysiology, 2nd edn. New York, NY: John Wiley & Sons. survivors. Dreaming 1: 11–21. Foulkes D (1985) Dreaming: A Cognitive-Psychological Analysis. Hinsdale, NJ: Nofzinger EA, Mintun MA, Wiseman M, Kupfer D, and Moore RY (1997) Forebrain Lawrence Erlbaum Associates. activation in REM sleep: An FDG PET study. Brain Research 770: 192–201. Foulkes D and Vogel G (1965) Mental activity at sleep onset. Journal of Abnormal Solms M (1997) The Neuropsychology of Dreams: A Clinico-Anatomical Study. Psychology 70: 231–243. Mahwah, NJ: Lawrence Erlbaum Associates. Hall CS and Van de Castle R (1966) The Content Analysis of Dreams. New York, NY: Solms M (2003) Dreaming and REM sleep are controlled by different brain Appleton-Century-Crofts. mechanisms. In: Pace-Schott E, Solms M, Blagrove M, and Harnad S (eds.) Hartmann E (2002) Dreaming. In: Lee-Chiong T, Sateia MJ, and Carskadon MA (eds.) Sleep and Dreaming: Scientific Advances and Reconsiderations, pp. 51–58. Sleep Medicine, pp. 93–98. Philadelphia, PA: Hanley & Balfus. New York, NY: Cambridge University Press. Hobson JA and McCarley RW (1997) The brain as a dream-state generator: Stickgold R (2003) Memory, cognition and dreams. In: Maquet P, Smith C, and Stickgold R An activation-synthesis hypothesis of the dream process. The American Journal of (eds.) Sleep and Brain Plasticity, pp. 17–39. New York, NY: Oxford University Press. Psychiatry 134: 1335–1348. Strauch I and Meier B (1996) In Search of Dreams: Results of Experimental Dream Koulack D (1993) Dreams and adaptation to contemporary stress. In: Moffitt A, Research. Albany, NY: State University of New York Press. Kramer M, and Hoffman R (eds.) The Functions of Dreaming, pp. 321–340. Witkin HA and Lewis HB (1967) Experimental Studies of Dreaming. New York, NY: Albany, NY: State University of New York Press. Random House.

ELSEVIER V Jain, Stanford Sleep Medicine Center, Redwood City, CA, USA

Published by Elsevier Inc.

Glossary data are often helpful in determining whether : Undesirable movements and behaviors that episodes are triggered by relative sleep occur during entry into sleep, within sleep, or in the setting deprivation. of arousals from sleep. Sleepwalking: Complex behaviors usually initiated during Sleep diaries: Records kept by the patient or family arousals from sleep culminating in ambulation during an member/partner that indicate sleep onset and offset altered state of consciousness and impaired judgment; also times, including and awakenings overnight; these referred to as somnambulism.

Description also published a twin study that reported a six-time greater concordance for sleepwalking among monozygotic twins Sleepwalking is characterized by complex behaviors that are than in dizygotic twins. typically initiated during arousals from sleep and result in Factors such as , fever, head injury, alcohol ambulation. The activity can vary from simple events such as abuse, hyperthyroidism, and other conditions have also been sitting up in to more complex movements such as walking shown to induce sleepwalking. The use of certain medications, or even ‘bolting’ from the room. These episodes can last from a including lithium, tricyclic (TCAs), phenothi- few seconds to several minutes long. Patients are generally azines, zolpidem, and other benzodiazepine receptor agonists, difficult to arouse during these periods, and if they are able to can also precipitate these events. Studies have also shown that be awakened, patients are often in a confused state. Many sleep-disordered breathing in children, that is, obstructive patients typically have their eyes open and have a ‘glassy- (OSA), may trigger sleepwalking due to the fre- eyed’ appearance during sleepwalking episodes. As these events quent arousals associated with respiratory events. Effective typically occur because of arousals from slow-wave sleep, they treatment of OSA may reduce the frequency of sleepwalking generally occur during the first half of the sleep period. episodes in some patients. While some patients may have little memory of the event, Overall, sleepwalking has been reported to have a 2% most patients generally have no memory of the event the follow- prevalence in the general population. Sleepwalking tends to ing morning. Patients may be able to recall emotions or impres- be more prevalent in childhood, peaking around age 8, and sions from the event. Symptoms of tachycardia, sweating, or the generally resolves with puberty although episodes have been expression of fear is generally not displayed in patients during an described in adults. While de novo sleepwalking can occur in episode. The absence of autonomic symptoms and screaming is adulthood, many adults who sleepwalk first exhibited sleep- what can differentiate a sleepwalking episode from sleep terrors. walking behavior in childhood. The persistence of sleepwalk- Sleepwalking is a subset of a larger group of parasomnias. ing into adulthood has been associated with underlying Parasomnias are undesirable movements and behaviors that psychopathology in a significant number of patients. occur during entry into sleep, during sleep, or with arousals from sleep. Parasomnias are subdivided into several categories: (1) disorders of arousal from non-REM sleep, (2) parasomnias Diagnosis and Differential Diagnosis associated with REM sleep, and (3) other parasomnias. The disorders of arousal include confusionalELSEVIER arousals, sleep- The most important initial approach to diagnosing sleepwalk- walking, and sleep terrors. The disorders of arousal tend to ing is to obtain a careful and detailed history from the patient occur in stage N3 sleep and therefore typically occur in the and their bed partner, parent, or caregiver. Information regard- first third of the night. ing the frequency, timing, and duration of the episodes should be obtained. It may be helpful to have patients keep a sleep diary to document this information. Detailed descriptions of Risk Factors any motor behavior should be obtained and the patient should be questioned about sensory symptoms. The clinician should There are a number of factors that may predispose a patient to pay particular attention to the patient’s past medical history, sleepwalking. There is a strong genetic influence in the devel- family history, and medication list to look for any precipitating opment of sleepwalking. Generally, if one or both parents have factors outlined above. If the patient relays a history of associ- had a history of sleepwalking, the child is at a significantly ated or apnea, they should also be evaluated for increased risk of developing sleepwalking episodes as well. The underlying sleep-disordered breathing. Finnish Twin Cohort study published by Hublin et al. reported While not required for a diagnosis, overnight polysomno- a concordance rate of 55% for monozygotic and 35% for graphy (PSG) can also be a valuable tool in the evaluation of dizygotic twins for sleepwalking in childhood. Bakwin et al. sleepwalking. Although rare, the occurrence of a complex

202 Encyclopedia of Sleep http://dx.doi.org/10.1016/B978-0-12-378610-4.00425-3 Descriptions of Parasomnias | Sleepwalking 203 behavior during PSG can support the diagnosis. While not schedules, and unfamiliar sleep environments can increase sleep- pathognomonic for sleepwalking, several PSG findings have walking episodes. If inciting agents are noted on the medication been thought to be associated with disorders of arousals. list, the precipitating agent should be avoided and the patient Patients with sleepwalking have been found to have an should be provided with a therapeutic alternative. If sleepwalking increased number of arousals from slow-wave sleep when activity remains problematic, pharmacologic therapy with ben- compared to matched controls. It has also been suggested that zodiazepines, TCAs, and selective reuptake inhibitors patients with a higher percentage of slow-wave sleep are at may provide benefit. Clonazepam at a dose of 0.5–2.0 mg ad- higher risk for disorders of arousals. However, studies of sleep- ministered at has been successful at controlling sleep- walkers have revealed that many have the same if not lower walking activity. slow-wave sleep activity when compared to matched controls. Also, arousals during slow-wave sleep can be seen in disorders other than sleepwalking such as OSA and periodic limb move- ments in sleep (PLMS). Hypersynchronous delta (HSD) activity Conclusion has been documented just before sleepwalking episodes in sev- eral studies. HSD waves consist of two or more high amplitude In conclusion, sleepwalking is a common parasomnia that is delta frequency waves that precede an arousal or complex be- most prevalent in children. There is a strong genetic influence, havior during sleep. Although sleepwalkers have been found to and many factors can precipitate sleepwalking episodes. The have higher ratios of HSD during slow-wave sleep, this finding diagnosis can be obtained from a careful and detailed history. has not been confirmed in more recent studies. Finally, as sleep- In more complicated cases, PSG may be used. Clinical suspicion disordered breathing has been postulated as a possible trigger of any underlying etiology warrants appropriate evaluation and for sleepwalking, evidence of OSA on PSG should prompt treat- treatment. The management of sleepwalking is typically straight- ment with nasal continuous positive airway pressure (nCPAP), forward with reassurance and counseling on safety precautions. as successful treatment has been reported to decrease or elimi- Finally, in refractory cases, pharmacotherapy may be warranted. nate the occurrence of sleepwalking. The differential diagnosis of sleepwalking includes other See also: Descriptions of Parasomnias: Confusional Arousals; NREM parasomnias such as confusional arousals and night Parasomnias in Children; Sleep Terrors. terrors and other sleep disorders, including nightmare disor- ders, behavior disorder (RBD), noc- turnal seizure activity, epileptic events, and sleep-related panic attacks. Sleepwalking can be differentiated from sleep terrors Further Reading by the lack of autonomic hyperactivity and loud scream during nocturnal episodes. Nightmare disorder and RBD both occur AASM (2005) International Classification of Sleep Disorders: Diagnostic and Coding within REM sleep and are more common in the second half of Manual, 2nd edn. Westchester, IL: American Academy of Sleep Medicine. the night. Also, children who are aroused from a nightmare Avidan AY and Kaplish N (2011) The parasomnias: Epidemiology, clinical features and generally become alert quickly and may often provide a de- diagnostic approach. Clinics in Chest Medicine 31: 353–370. Bakwin H (1970) Sleepwalking in twins. The Lancet 2: 466–467. tailed description of their dream content. If there is concern Barabas G, Ferrari M, and Matthews WS (1983) Childhood migraine and regarding epileptic activity, nocturnal PSG should be somnambulism. Neurology 33: 948–949. performed with an expanded seizure montage. Patients with Berry R (2012) Fundamentals of Sleep Medicine, pp. 567–592. Philadelphia PA: sleep-related panic attacks typically develop autonomic activa- Elsevier Saunders. Broughton RJ (1968) Sleep disorders: Disorders of arousal? Enuresis, somnambulism, tion following arousal from sleep and lack the confusion and and nightmares occur in confusional states of arousal, not in "dreaming sleep". amnesia seen in sleepwalkers. Science 159: 1070–1078. Broughton R (2000) NREM parasomnias. In: Kryger MHRT and Dement WC (eds.) Principles and Practice of Sleep Medicine, pp. 693–706. Philadelphia, PA: W.B. Management Saunders. ELSEVIERChokroverty SHW and Walters AS (2003) An approach to the patient with movement disorders during sleep and classification. In: Chokroverty SHW and Walters AS Management of sleepwalking should focus on both attempting to (eds.) Sleep and Movement Disorders, pp. 201–218. Philadelphia, PA: eliminate the occurrence of the events and mitigating the adverse Butterworth-Heinemann. effects of a potential episode. Patients with other sleep, medical, Espa F, Dauvilliers Y, Ondze B, Billiard M, and Besset A (2002) Arousal reactions in sleepwalking and night terrors in adults: The role of respiratory events. Sleep or psychiatric disorders should obtain appropriate treatment for 25: 871–875. the underlying disorder. Next, patients should be provided reas- Goodwin JL, Kaemingk KL, Fregosi RF, et al. (2004) Parasomnias and sleep surance and counseling regarding safety precautions in the home. disordered breathing in Caucasian and Hispanic children – the Tucson children’s Patients and their parents, bed partners, or caregivers should be assessment of sleep apnea study. BMC Medicine 2: 14. reassured that many arousal disorders decline in frequency, as a Guilleminault C, Palombini L, Pelayo R, and Chervin RD (2003) Sleepwalking and sleep terrors in prepubertal children: What triggers them? Pediatrics child enters adolescence. The clinician should ensure that 111: e17–e25. counseling regarding environmental protection is provided. Hublin C, Kaprio J, Partinen M, et al. (1997) Prevalence and genetics of sleepwalking: Safety measures include locks on doors and windows, sleeping A population-based twin study. Neurology 48: 177–181. on the first level of the home, gates across stairs, removing sharp Kales JD, Kales A, Soldatos CR, Chamberlin K, and Martin ED (1979) Sleepwalking and night terrors related to febrile illness. The American Journal of Psychiatry objects from the , avoiding bunk beds, and placing 136: 1214–1215. padding or mattresses next to the bed. Emphasis should also be Kales A, Soldatos CR, Bixler EO, et al. (1980) Hereditary factors in sleepwalking and placed on sleep hygiene, as sleep deprivation, irregular sleep night terrors. The British Journal of Psychiatry 137: 111–118. 204 Descriptions of Parasomnias | Sleepwalking

Laberge L, Tremblay RE, Vitaro F, and Montplaisir J (2000) Development of Pesikoff RB and Davis PC (1971) Treatment of pavor nocturnus and somnambulism in parasomnias from childhood to early adolescence. Pediatrics 106: 67–74. children. The American Journal of Psychiatry 128: 778–781. Mahowald M (2002) Arousal and sleep-wake transition parasomnias. Robinson A and Guilleminault C (2003) Disorders of arousal. In: Chokroverty SHW and In: Lee-Chiong TLSM and Carskadon MA (eds.) Sleep Medicine, pp. 207–213. Walters AS (eds.) Sleep and Movement Disorders, pp. 265–272. Philadelphia, PA: Philadelphia, PA: Hanley and Belfus. Butterworth-Heinemann. Mindell JA and Owens J (2003) Sleepwalking and sleep terrors. A Clinical Guide to Rosen GM, Ferber R, and Mahowald MW (1996) Evaluation of parasomnias in children. Pediatric Sleep. Philadelphia, PA: Lipincott Williams &Wilkins. Child and Adolescent Clinics of North America 5: 601–616.

ELSEVIER Special Conditions, Disorders, and Clinical Issues of SRMD

Contents Gender Differences in Sleep-Related Movement Disorders Sleep-Related Movement Disorders in Children Age-Related Changes in PLMS Characteristics of RLS Patients Medication Effects and Sleep-Related Movement Disorders Restless Legs Syndrome in Internal Medicine Impact of Psychiatric Disorders on Sleep-Related Movement Disorders

Gender Differences in Sleep-Related Movement Disorders B Phillips, University of KY College of Medicine, Lexington, KY, USA; UK GSH Hospital, Lexington, KY, USA

ã 2013 Elsevier Inc. All rights reserved.

Glossary more than 15 times per hour in adults (or more than five Periodic limb movements (PLMs): Stereotyped times per hour in children) and is associated with sleep and repetitive limb movements that occur during disturbance and/or daytime fatigue or sleepiness. sleep. Sleep-disordered breathing (SDB): This describes a group Periodic limb movement disorder (PLMD): A sleep of disorders characterized by abnormalities of respiratory disorder characterized by stereotyped and repetitive pattern (pauses in breathing) or the quantity of ventilation limb movements that occur during sleep at the rate of during sleep.

Restless Legs Syndrome specificity of these criteria is not ideal, but careful application of the first four features, accompanied by a physical examina- Clinical Features tion (to rule out neuropathy and vascular disease), is fairly Restless legs syndrome (RLS) is a sleep-related movement dis- specific for RLS. The differential diagnosis includes cramps, order whose cardinal feature is unpleasant leg sensations, typ- positional discomfort, vascular leg disease, and neuropathy. ically occurring at night, that interfere with sleep. The sensation Adding response to dopaminergic medication to the essential is probably most aptly described as a powerful urge to move criteria improves diagnostic accuracy. the legs; it is rarely described as painful, and the possibility of neuropathy should be consideredELSEVIER when the discomfort Epidemiology presents primarily as pain. There is a circadian variation in symptoms, with greatest intensity typically occurring between In population-based surveys, typically conducted by phone, the 10 p.m. and 2 a.m. Symptoms are worse at rest and improve prevalence of any degree of RLS symptoms is estimated to be with movement or stimulation, including walking, rubbing, somewhere between 10% and 15% for all adults, with lower rates and stretching. The distressing sensations most typically in- in the young and higher in the elderly. However, the prevalence volve the legs, but can also occur in the arms. Because of the of RLS varies considerably with different criteria for frequency nature and timing of RLS symptoms, patients with RLS may and severity. For example, in the restless legs syndrome preva- present with sleep-onset . lence and impact Restless Legs Epidemiology Symptoms and Treatment (REST) study, RLS symptoms were endorsed by 7.2% of the survey population. However, symptoms occurring at least Diagnosis twice per week were reported by only 5% of the subjects and were The diagnosis of RLS is made by history and physical exami- moderately or severely distressing in only 2.7%. nation based on criteria listed in Table 1. The rate of RLS may be lower in Asian than in European Thus, the diagnosis is based on subjective criteria alone, and populations, but the prevalence in African Americans is similar (PSG) is not generally necessary. The to that of Caucasians.

Encyclopedia of Sleep http://dx.doi.org/10.1016/B978-0-12-378610-4.00404-6 109 110 Special Conditions, Disorders, and Clinical Issues of SRMD | Gender Differences in Sleep-Related Movement Disorders

Table 1 Diagnostic criteria for RLS in adults paroxetine, citalopram, and amitriptyline was more likely to be associated with RLS symptoms in men. A. The patient reports an urge to move the legs, usually accompanied or Augmentation (worsening of symptoms despite treatment) caused by uncomfortable and unpleasant sensations in the legs. B. The urge to move or the unpleasant sensations begin or worsen occurs in a large percentage of patients treated with levodopa. during periods of rest or inactivity such as lying or sitting. Data on the prevalence of augmentation with ago- C. The urge to move or the unpleasant sensations are partially or totally nists are still scant, but this phenomenon has been documen- relieved by movement, such as walking and stretching, or at least as ted to occur with these agents. One study reported a prevalence long as the activity continues. rate of about 12% with dopamine agonists, with low ferritin D. The urge to move or the unpleasant sensations are worse, or only being the primary associated risk. In that study, there were no occur, in the evening or night. gender differences in the rate of augmentation. E. The condition is not better explained by another current , medical or neurological disorder, , medication use, or substance use disorder. Associative, Predisposing, and Precipitating Factors

From American Academy of Sleep Medicine (2005) International Classification of Two recent genome-wide association studies have reported Sleep Disorders: Diagnostic and Coding Manual, 2nd edn., p. 180. Westchester, IL: positive association with sequence variants in or around spe- American Academy of Sleep Medicine. cific genes on chromosomes 6p, 2p, and 15q and having symptoms of RLS (and periodic limb movements). Serum ferritin levels are lower in those with the genetic variant that predisposes to RLS, which supports the hypothesis that iron Gender Differences for RLS depletion or dysfunction is somehow involved in the patho- RLS affects women disproportionately. A consistent finding in genesis of the disease. Dopamine deficiency or dysfunction is the literature about RLS is that women are 1.5–2 times as likely also in the pathophysiology of RLS, and one unifying hypoth- as men are to report RLS symptoms. Studies in both children esis is that impairment of dopamine transport or function in and adolescents have demonstrated that this difference does the central nervous system due to reduced iron may contribute not usually develop until the second or third decade of life. to the development of this disorder. However, after the third decade, women are about twice as Primary RLS occurs without a known predisposing or exac- likely as men to endorse RLS symptoms, and the likelihood erbating condition, is more likely to have earlier age of onset, of having RLS may be related to pregnancy. Pregnancy is an and is likely to be familial. RLS can also be ‘secondary’ to important risk factor for RLS, both during the pregnancy and in another condition, including especially iron deficiency, preg- subsequent years. About a fourth of pregnant women experi- nancy, and renal failure. ence RLS symptoms, which typically peak in severity in the A large group of conditions has now been reported to be third trimester and resolve promptly after delivery. Lower he- associated with RLS. Many of these conditions and disorders moglobin, mean corpuscular volumes, and serum folate levels also lack objective diagnostic criteria, such as attention deficit appear to be risk factors for RLS in pregnancy. With aging, the hyperactivity disorder, depression, and fibromyalgia, and risk of RLS is fairly level for men, but it increases for women, many occur with increased frequency in women. proportionate to parity. In one study, nulliparous women had the same risk for RLS as did men up to the age of 64. However, Complications and consequences for women who had borne children, the risk of RLS increased Individuals with RLS are at increased risk for mood distur- with the number of children. A woman with one child had bance, according to cross-sectional studies. This is not neces- twice the risk of RLS as a nulliparous woman and the risk sarily a causal relationship; mood disturbance could contribute increased with additional children. Indeed, a recent publica- to endorsement of RLS symptoms. Like RLS, depression occurs tion by Pantaleo et al. indicated that pregnancy accounts for with increased frequency in women compared to men and could almost all of the gender differences reported in overall RLS partly account for the increased prevalence of RLS symptoms in prevalence. ELSEVIERwomen. The effects of RLS symptoms on daytime function are The gender difference in RLS symptoms appears to be not clear. RLS has variously been reported to be associated with present for both primary and secondary RLS. In a large cross- daytime sleepiness as well as not to impair daytime sleepiness sectional study of patients with end-stage renal disease (ESRD), and alertness. It does, however, appear to adversely affect quality women were much more likely than men were to endorse RLS and quantity of nocturnal sleep. RLS appears to be associated symptoms. Other associated factors for RLS in ESRD include with many significant medical conditions and may be a marker lower hemoglobin, worse subjective and objective sleep qual- for poor overall health. Indeed, one study has reported an in- ity, excessive daytime sleepiness, use of sleeping pills, depres- creased risk of death in individuals with RLS. sive symptoms, and higher risk of both and hypertension. Management RLS is frequently reported to occur with use. It appears likely that the association between RLS and antide- Nonpharmacologic treatment pressant use varies by gender and by type of antidepressant. Elimination of factors that may cause or contribute to RLS Indeed, antidepressants were more strongly associated with may make a difference. Several medications have been linked RLS for men than for women in one study. But analyses of to both RLS and periodic limb movements, and the data individual agents showed that fluoxetine was more strongly are particularly strong for the association between RLS and associated with RLS in women than in men, whereas use of antidepressants. Lifestyle relates to RLS symptoms: increased Special Conditions, Disorders, and Clinical Issues of SRMD | Gender Differences in Sleep-Related Movement Disorders 111 weight, intake, and smoking have been associated Periodic Limb Movements with increased likelihood of endorsing RLS symptoms. RLS is also associated with earning a lower income, sedentary RLS and periodic limb movements frequently coexist, which lifestyle, and reduced alcohol consumption. Nonpharmaco- has resulted in much confusion about periodic limb move- logic measures therefore should include education, moderate ments. Periodic limb movements of sleep (PLMS), originally exercise, smoking cessation, caffeine reduction or elimina- called nocturnal myoclonus, are rhythmical kicking of the tion, and discontinuation of exacerbating medications if it is lower extremities. They increase with age and are most com- safe to do so. Some have found that working at night and monly identified in association with other sleep disorders. sleeping in the day has helped. Iron supplementation should While an overwhelming majority (>80%) of RLS patients be given to those who are iron deficient. have periodic limb movements, only a fraction of those individuals who have limb movements during sleep have Pharmacologic treatment RLS. PLMS have also been included in the obstructive sleep Dopamine receptor agonists are the first-line treatment and apnea hypopnea syndrome (see Figure 1), the upper airway are the only agents that are Food and Drug Administration resistance syndrome, , and REM sleep behavior (FDA)-approved for RLS. The two dopamine receptor agonists disorder. PLMS are also frequently seen in patients who are available for this purpose in the United States are ropinirole taking antidepressants and probably represent a serotonergic and pramipexole; both are FDA-approved. Pramipexole is ren- phenomenon. When patients with complaints of insomnia À1 ally excreted, and the dose is 0.125–0.75 mg day in single or or have PLMS and no other sleep disorder or À1 divided doses, averaging 0.25 mg day . Ropinirole is hepati- relevant (e.g., antidepressant) medication use is present, cally excreted, and the effective dose is in the range of 1.5–6 mg they may be diagnosed with periodic limb movement disor- À1 À1 day in single or divided doses, averaging about 2 mg day . der (PLMD). Such patients are probably rare. Patients with The main side effects of these agents are nausea, vomiting, PLMS associated with RLS symptoms should be treated for orthostasis, dizziness, sleepiness, insomnia, and compulsive RLS, but there is no evidence to support pharmacologic behavior. Because of delays in absorption, these agents treatment of PLMS/PLMD, and there is no agent FDA- work best if given at least an hour before symptom onset approved for this indication. The revised diagnostic criteria typically occurs. for PLMD take into account the coexistence of leg jerks with Use of other agents is off-label and not clearly supported by many medical conditions and medications, and also ‘raise the literature. As mentioned, RLS is a particular issue in preg- the bar’ for the ‘abnormal’ number of periodic limb move- nancy. None of the medications commonly used to treat RLS is ments from 5 to 15 for adults (Table 2). safe in pregnancy. For pregnant women, folic acid has been reported to improve symptoms in those who are folate defi- cient. Iron replacement may also reduce or eliminate symp- À Gender Differences in Periodic Limb Movements toms in patients who have serum ferritin levels below 45 mgl 1. Recently, pneumatic compression devices have been shown to Women may be more likely to have periodic limb movements relieve symptoms in a randomized, double-blinded, sham- than are men because they are more likely to be diagnosed with controlled trial. depression and to be taking antidepressants. In addition, they One consideration in the pharmacologic treatment of RLS are more likely to have subtle or occult sleep-disordered is the rather large placebo effect, which has been reported to be breathing (e.g., upper airways resistance syndrome) than are about 40%. Another consideration in the pharmacologic man- men, and the resulting arousal-associated leg jerks may be agement of RLS is the appearance of augmentation. The Inter- misdiagnosed as PLMD. national Restless Legs Study Group has established diagnostic standards for the dopaminergic augmentation of RLS, based on usual time of RLS symptom onset each day, number of body parts with RLS symptoms, latency toELSEVIER symptoms at rest, severity of the symptoms, time of occurrence, and effects of dopami- nergic medication on symptoms. In brief, augmentation Sleep-related bruxism is characterized by repetitive clenching may be said to have occurred if the symptoms have spread to or grinding of the teeth during sleep. The primary conse- other body parts (e.g., from calves to thighs), occur earlier in quences of this are tooth wear and jaw pain. Bruxism prob- the evening than originally, or increase in severity. Augmenta- ably has a prevalence of about 15% and is highest in tion occurs frequently with the (off-label) regular use of childhood. Bruxism tends to occur in families. Anecdotally, carbidopa; it also occurs, but much less frequently, with ropi- bruxism is thought to be associated with anxiety, stress, nirole and pramipexole. Evidence-based recommendations for tooth malocclusion, or a side effect of medications such as management of augmentation are lacking, but some suggested antidepressants. It has also been reported with sleep apnea, strategies are to take the dose earlier in the day and split the Huntingdon’s disease, and Parkinson’s disease. Use of existing dose into early evening and bedtime doses. Augmen- splints or tooth guards, made by a dentist, is the most tation and progression of the disease are difficult, if not im- common form of treatment, but behavioral therapy, bio- possible, to distinguish. This, coupled with the large placebo feedback, botulinum toxin, and correction of misaligned effect associated with any treatment for this condition, results teeth may also be effective. in the lack of a clear-cut approach to the management of There are no reported gender differences in the prevalence, augmentation. manifestations, or treatment of bruxism. 112 Special Conditions, Disorders, and Clinical Issues of SRMD | Gender Differences in Sleep-Related Movement Disorders

~LEOG 0

~REOG 0

~C3A2 0

~C4A1 0

~O1A2 0

~O2A1 0

~Chin 0

Flow 128

Pressure 0 00 98 96 98 98 97 97 99 98 98 98 99 98 98 SAO2 90 95 95 96 93 93 94 93 93 95 96 95 94 95 95 96

Micro 128

Chest 128

ABD 128 S S S SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS Body

~Left Leg 0

~Right Leg 0

Stage 2 S2 S2 S2 S2 S2 S2 S2 S2 S2 S2 S2 S2 S2 S2 S2 S2 S2 S2 S2 S2 S2 S2 S2 S2 S2 S2 S2 S2 202 203 203 204 204 205 205 206 206 207 207 208 208 209 209 210 210 211 21 60" 120" 180" 240" 5 min.

Figure 1 In this 5-min, compressed PSG tracing, periodic limb movements are seen in the leg lead channels (‘left leg, right leg’). However, inspection reveals that these leg movements are part of the arousal response to obstructive respiratory events, seen clearly in the respiratory channel (‘flow, pressure’). This common finding likely accounts for many cases of ‘periodic limb movement disorder (PLMD)’ and is a major reason why the diagnosis of PLMD should be made only after careful exclusion of sleep-disordered breathing, medication side effects, or other causes of movement.

Table 2 Diagnostic Criteria for Periodic Limb Movement Disorder See also: Psychiatric Associations of Sleep Loss/Deprivation: A. Polysomnography demonstrates repetitive, highly stereotyped, limb Antidepressant Effects of Sleep Manipulation; Special Conditions, movements that are: Disorders, and Clinical Issues for Insomnia: Gender 1. 0.5–5 s Differences; Special Conditions, Disorders, and Clinical Issues 2. Of amplitude >25% of toe dorsiflexion during calibration of SRBD: Gender-Specific Differences in Patients with Obstructive 3. In a sequence of four or more movements Sleep Apnea–Hypopnea Syndrome; Special Populations Affected 4. Separated by an interval of more than 5 s (from limb-movement by Sleep Loss/Deprivation: Pregnancy and Postpartum. onset) and less than 90 s (typically an interval of 20–40 s) B. The PLMS index exceeds 5 per hour in children and 15 per hour in most adult cases C. There is clinical sleep disturbance or a complaint of daytime fatigue D. The PLMS are not better explained byELSEVIER another current sleep disorder, Further Reading medical or neurological disorder, mental disorder, medication use, or a substance use disorder Allen RP, Walters AS, Montplaisir J, et al. (2005) Restless legs syndrome prevalence and impact: REST general population study. Archives of Internal Medicine 165: Note: If PLMS are present without clinical sleep disturbance, the PLMS can be noted as 1286–1292. a polysomnographic finding, but criteria are not met for a diagnosis of PLMD. American Academy of Sleep Medicine (2005) International Classification of Sleep From American Academy of Sleep Medicine (2005) International Classification of Sleep Disorders: Diagnostic and Coding Manual, 2nd edn., p. 185. Westchester, IL: Disorders: Diagnostic and Coding Manual, 2nd edn., p. 185. Westchester, IL: American American Academy of Sleep Medicine. Araujo SM, de Bruin VM, Nepomuceno LA, et al. (2010) Restless legs syndrome in Academy of Sleep Medicine. end-stage renal disease: Clinical characteristics and associated comorbidities. Sleep Medicine 11: 785–790. Aukerman MM, Aukerman D, Bayard M, Tudiver F, Thorp L, and Bailey B (2006) Exercise and restless legs syndrome: A randomized controlled trial. Journal of the American Board of Family Medicine 19: 487–493. Other Sleep-Related Movement Disorders Baughman KR, Bourguet CC, and Ober SK (2009) Gender differences in the association between antidepressant use and restless legs syndrome. Movement Disorders 24: 1054–1059. Other sleep-related movement disorders include leg cramps Benesˇ H, von Eye A, and Kohnen R (2009) Empirical evaluation of the and movement disorders due to drugs or medical conditions. accuracy of diagnostic criteria for restless legs syndrome. Sleep Medicine Data about gender differences in these conditions are lacking. 10: 524–530. Special Conditions, Disorders, and Clinical Issues of SRMD | Gender Differences in Sleep-Related Movement Disorders 113

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