ERS School Course Sleep Medicine: Non-Respiratory Causes of Excessive Daytime Sleepiness

breathe reviews.qxd 01/03/2006 18:09 Page 29 REVIEW The ERS designates this ERS School Course educational activity for a maximum of 1 CME credit. For Sleep Medicine information on how to earn CME credits, see page 292. Non-respiratory causes of excessive daytime sleepiness V. Viot-Blanc Unité de Sommeil Hôpital Lariboisière 2 rue Ambroise Pare 75010 Paris France Fax: 33 149958313 E-mail: [email protected] Educational aims k To present the symptoms, methods of assessment and the different causes of excessive daytime sleepiness when nocturnal respiratory disturbances have been excluded. k To enable physicians to confirm a diagnosis of sleepiness and recognise the pathology. Summary Excessive daytime sleepiness (EDS) is defined as an inability to stay awake and alert during the major waking episodes of the day, resulting in unintended drowsiness or sleep episodes almost daily for at least 3 months. This review will examine the assessment of sleepiness and different causes of EDS. factors (time of day) and sleep debt (sleep Physiopathology duration and fragmentation). Wake propensity Sleepiness is the result of the combined effects depends on external (environment, exercise, of sleep propensity and wake propensity (fig- drugs, etc.) and internal factors, such as the diff- ure 1). Sleep propensity depends on circadian erent types of hypersomnia or other medical Breathe | March 2006 | Volume 2 | No 3 245 breathe reviews.qxd 01/03/2006 18:09 Page 30 REVIEW ERS School Course Figure 1 Schematic examining the causes Sleep debt of sleepiness. Sleep fragmentation Internal factors Environment Internal clock Trait (?) Sleep propensity Wake propensity Sleepiness disorders usually responsible for EDS. For both severe sleepiness. Dozing whilst driving is excep- sleep and wake propensity, individual factors tionally dangerous and, therefore, it is very play a key role concerning the level of sleepiness important to ask patients about their profession- of each subject. al or leisure activities. The consequences of EDS on daily life (profession, studies, family or social life) have been clearly demonstrated, as well as Clinical presentation on quality of life. EDS may consist of one or more of the following symptoms: reaction retardation, attention or Clinical interview memory lapses, severe difficulty waking up in the morning, constant drowsiness, the need to A complete clinical interview will determine the fight against sleepiness, difficulty staying awake, following information from patients: the course dozing or falling asleep (more or less under con- of sleepiness during daytime, especially at wake trol) and frequent naps (refreshing or not). time; the occurrence of naps, if they are refresh- Falling asleep is more likely to happen when the ing or not; the circumstances of falling asleep, i.e. subject is in a quiet, warm, dark, less stimulating adapted or not, dangerous, under control or not; situation. Falling asleep or dozing can be more the history of the disease, i.e. age of onset, trig- or less clearly perceived by the patient and can gering factors, fluctuations, seasonal influence; be more or less under control. Reading, watching medical history and treatments; the sleep need, television and being a passenger on a bus or a and the habitual sleep duration and sleep sched- train are examples of situations where this can ule, the influence of work schedule; and the occur. Falling asleep or dozing while talking, sleep timing the patient would choose if allowed walking or being physically active are signs of to do so. Figure 2 20 h 22 h 24 h 2 h 4 h 6 h 8 h 10 h 12 h 14 h 16 h 18 h 20 h Example of a sleep log. Sleep Lights off on Nap Sleepiness Falling asleep Daytime Treatment 246 Breathe | March 2006 | Volume 2 | No 3 breathe reviews.qxd 01/03/2006 18:09 Page 31 ERS School Course REVIEW complete, resulting in a progressive fall to the Educational questions Clinical assessment floor, or limited, affecting a specific part of the At a clinical interview, if your of sleepiness body, e.g. face, neck, hands, knee. Cataplexy usually follows EDS in the course of the disease by patient replied "yes" to the The Epworth Sleepiness Scale is a simple and 1–2 years. following questions, what useful tool to confirm the level of sleepiness and Cataplexy is not necessary to diagnose nar- pathology would you supect measure improvement following treatment. It colepsy. In the form "narcolepsy without cata- if EDS is present? assesses the likelihood of patients falling asleep plexy", cataplexy is not present and does not 1. Do you feel strange when or dozing in eight different situations during appear later. The CSF level of hypocretine is high- you laugh or are emo- previous weeks, using a scale of 0–3, where 0 is ly variable in these cases and does not aid the tional? "never doze" and 3 is "strong". A total score of 10 diagnostic process. The diagnosis will be con- 2. Do you usually sleep ≥10 is generally taken to indicate EDS. firmed by the multiple sleep latency test (MSLT), hours? The sleep log (figure 2) can also be used for which reveals mean sleep latency to be 8 min- 3. Do you get less sleep clinical assessment. It is completed by the ≤ utes (often <5 minutes) and 2 SOREMPs. The than you need? patient for 3 weeks and provides a lot of infor- ≥ ≥ MSLT is carried out over 4–5 naps, during which 4. Do you take sedative mation regarding daytime sleepiness, usual sleep-onset latency is measured and sleep record- treatment on a regular sleep duration and sleep schedule. It is also use- ed over 15 minutes. basis? ful when assessing treatment efficacy. A familial pattern has been described for nar- 5. Do you go to bed late colepsy, but the probability of a narcoleptic par- and get up late? Pathologies suspected ent transmitting the disease to his/her children when EDS is present is 1–2 per 100. Cataplexy should be specifically treated Narcolepsies when severe, usually by antidepressants, such as Narcolepsies have a reported prevalence of 2–18 fluoxetine. per 10,000 inhabitants. Beside sleepiness, the disease is characterised by the irruption of rapid eye movement (REM) sleep during wakefulness, Idiopathic hypersomnias as well as during sleep. The disease usually Idiopathic hypersomnias (IHs) are characterised appears between 15 and 25 years of age, but by EDS with long frequent naps, often described may appear at any age. Narcolepsy is caused by as non-restorative. Two different types have been the degeneration of a small group of neurones described. 1) IH with long sleep time is defined situated in the ventrolateral nucleus of the by the presence of EDS accompanying a long hypothalamus, containing a recently discovered nocturnal sleep time (>10 hours), with difficul- peptide named hypocretine or orexine, which ties waking up in the morning or after non- stabilises wake and sleep states. The levels in the refreshing naps. 2) IH without long sleep time cerebrospinal fluid (CSF) are dramatically associates EDS with normal usual sleep time decreased, if not absent, in the clinical form (6–10 hours per day) and a mean sleep latency "with cataplexy". of <8 minutes at MSLT. In addition, there should The main symptom is severe EDS charac- be no SOREMP or no more than one, differenti- terised by lapses into sleep and frequent refresh- ating IH from narcolepsy without cataplexy. A ing naps. Nocturnal sleep is often described familial pattern has been described occasionally, as light, unstable and fragmented. Poly- but the precise cause of the disease still remains somnographic recordings performed during the unknown. night usually present severely fragmented and/or disturbed sleep, as well as short REM The first-line treatment of EDS in narcolepsy and sleep latency or sleep-onset REM periods IH is modafinil with a dose ranging 100–400 (SOREMPs; <20 minutes). Others signs might mg per day. also be present, such as frightening hallucin- ations at sleep onset or offset and sleep paraly- Behaviourally induced insufficient sis, but these can be present in normal subjects. sleep syndrome Cataplexy is present only in narcolepsy and This syndrome occurs when an individual per- is sufficient to diagnose this form of the disease: sistently fails to obtain the amount of sleep "narcolepsy with cataplexy". Cataplexy is required to maintain normal levels of alertness or characterised by a sudden loss of muscular tone wakefulness. The result is a voluntary but un- triggered by positive emotions like laugher, intentional chronic sleep deprivation. The clinical pride, elation or surprise. Cataplexy can be interview reveals a substantial disparity between Breathe | March 2006 | Volume 2 | No 3 247 breathe reviews.qxd 07/03/2006 15:17 Page 32 REVIEW ERS School Course subjects and the first complaint can be severe sleep-onset insomnia with a preference for late wake-up times. When forced to wake up earlier than desired, the patient can be very sleepy and sometimes unable to wake up by himself. When a repeated "early" wake-up time is socially required, the subject becomes sleepy during the daytime due to sleep debt. Nevertheless, sleepiness usually disappears in the evening. A familial pattern has been described, and the origin of the disease is probably genetic combined with psychological and behavioural aspects. Treatment with phototherapy or chrono- therapy is more efficient than hypnotic treatment. Medical condition- and treatment- sleep needs and the sleep amount actually related EDS obtained. During holidays, sleep duration may or Table 1 shows some medical conditions where may not increase. EDS may be present. Table 2 shows the groups of drugs that can cause EDS in patients.

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