Assessment of Daytime Sleepiness: A Practical Approach

Assessment of Daytime Sleepiness: A Practical Approach



















There are 2 common methods of measuring daytime sleepiness: the Multiple Sleep Latency Test (MSLT) and the Epworth Sleepiness Scale (ESS).Multiple Sleep Latency Test










The differential diagnosis of excessive daytime sleepiness is presented in Table 3. Chronically insufficient sleep is probably the most common cause of sleepiness, given the prevalence of sleep deprivation in adults.2,3,5,23 However, this diagnosis is rarely made, because chronic sleep deprivation is not generally viewed as a medical problem.

The 2 major characteristics of chronically insufficient sleep are habitual sleep episodes that are shorter in duration than is expected for age (generally, 7 to 8 hours for adults) and longer than normal sleep episodes on weekends or vacations. Other diagnostic clues in the history include the patient's work schedule, number of jobs, family and other social obligations, and hours of television and Internet use.

Chronically insufficient sleep is a clinical diagnosis based on the patient's sleep and social history. However, many patients with other sleep disorders also have insufficient sleep. Therefore, it is important to consider other causes before deciding that insufficient sleep is the only cause of a patient's daytime sleepiness.

OSAHS is characterized by recurrent collapse of the upper airway during sleep; the episodes of collapse are associated with oxyhemoglobin desaturation and recurrent arousals.24 Patients generally present with a complaint of loud snoring that is bothersome to the bed partner, witnessed apneas, nocturnal gasping and choking, morning headaches, and nonrefreshing sleep.

Obesity is the most common finding on physical examination. Other common abnormalities associated with OSAHS include tonsillar hyperplasia, crowding of the oropharynx, lateral narrowing of the pharyngeal walls, an enlarged tongue, and retrognathia. OSAHS is diagnosed by polysomnography; therefore, referral to a sleep center is recommended.

Narcolepsy is a chronic neurologic condition characterized by both excessive daytime sleepiness and impaired regulation of REM sleep.25,26In addition to daytime sleepiness, narcoleptic patients often have cataplexy, hypnagogic hallucinations, and sleep paralysis.

Cataplexy, considered pathognomonic of this disorder, is sudden muscle weakness brought on by intense emotion, such as anger, or by laughter. The muscle weakness can affect any muscle group and manifest as falling, facial or head droop, or dropping objects.

Hypnagogic hallucinations (intense, dreamlike hallucinations at the beginning of the night soon after the patient falls asleep) and sleep paralysis (profound weakness of the skeletal muscles, generally occurring during awakenings) are not specific to narcolepsy; both have been reported by patients with severe OSAHS or idiopathic hypersomnia, and sleep paralysis can also occur as a sporadic parasomnia. Because a nocturnal sleep study and an MSLT are often required for the diagnosis of narcolepsy, especially in cases without cataplexy, referral to a sleep specialist is recommended.

The restless legs syndrome (RLS) is characterized by a feeling of motor restlessness or urge to move the legs that is relieved with leg movement and occurs while sitting or lying down, typically in the evening.27 RLS is often associated with recurrent leg kicking during sleep, the main feature of PLMD.

RLS may present as insomnia because the restlessness prevents the patient from falling asleep; however, daytime sleepiness can also be the presenting symptom if there are prominent leg movements during sleep. RLS is diagnosed clinically, requiring only the presence of the symptoms noted above, while PLMD is diagnosed by sleep study.

PLMD is characterized by repetitive, rhythmic limb movements during sleep, particularly during the first half of the night. The limb movements are generally associated with arousals from sleep.

Approximately 80% of patients with RLS have PLMD. However, most patients with PLMD that has been documented by sleep study do not have the characteristic features of RLS. PLMD is frequently seen in patients with OSAHS and narcolepsy. Whether the finding of PLMD on sleep study is clinically significant in the absence of an association with another sleep disorder is controversial.

Disorders of the sleep-wake cycle are often characterized by a misalignment between the patient's sleep cycle and the societal norm (generally a bedtime between 10 pm and midnight with awakening between 6 and 8 am).28 Most shift workers, particularly those with night shifts or frequently rotat- ing shifts, complain of excessive sleepiness because it is difficult to achieve normal sleep when the major sleep episode begins in the morning.29

Patients with delayed sleep phase syndrome tend to go to bed after midnight (bedtime is delayed relative to the societal norm) and, if allowed, will generally sleep uninterruptedly for 7 to 8 hours, awakening refreshed. The shifted sleep pattern becomes abnormal when the patient must awaken earlier than his or her optimal time, usually because of employment. The correspondingly shortened sleep time leads to insufficient sleep and excessive sleepiness.

Idiopathic hypersomnia is characterized by constant daytime sleepiness and frequent daytime sleep episodes lasting 1 hour or more that are generally not refreshing.26,30 The MSLT demonstrates moderate to severe shortening of the daytime sleep latency (less than 10 minutes), but there is generally no REM during any of the naps.

Idiopathic hypersomnia is difficult to diagnose, in part because there are no clear diagnostic criteria. It is usually diagnosed only after patients have had a full sleep evaluation--including a sleep log, polysomnography, and MSLT--and after ruling out other causes of daytime sleepiness, particular- ly chronically insufficient sleep, OSAHS, narcolepsy, and RLS.APPROACH TO THE SLEEPY PATIENT

A systematic approach is important to the evaluation and treatment of patients who present with excessive daytime sleepiness. Those identified as possibly having OSAHS, RLS, or narcolepsy need prompt referral to a sleep center for proper evaluation and treatment. Other patients, particularly those who are not getting sufficient sleep or who are taking medications that are associated with sedation, can be treated initially by their primary care physicians.

Identification of these patients begins with asking whether they are excessively sleepy during the day. If the answer is yes, there are 6 simple follow-up questions to ask (Figure).

 Do you snore? If the answer is yes and the snoring is loud, habitual, and/or bothersome, OSAHS is a likely possibility. However, it is important to remember that the absence of snoring does not rule out sleep apnea. Referral to a sleep center for a sleep study or to a clinician experienced with the problem is recommended for all patients with suspected OSAHS.

 Do your legs feel restless when you relax, or do your legs kick at night? If the answer is yes, consider the possibility of RLS. Referral to a sleep specialist for a full evaluation and management is recommended.

 Do you have weakness in any muscle when you experience sudden or strong emotion? This question attempts to identify cataplexy. If the patient has cataplexy or any of the other major symptoms or signs of narcolepsy, referral to a sleep center for a sleep study and MSLT is recommended.

 What is your sleep schedule? If the patient's sleep schedule is outside the above-mentioned societal norm or if the patient works shifts, a sleep-wake cycle disorder must be considered. Referral to a sleep center is recommended.

 What medications do you take? The physician should obtain a complete list of medications, including common OTC agents. If the patient is taking a medication associated with daytime sleepiness, the physician should make a therapeutic substitution if possible (and when appropriate).

 How much sleep do you get? Do you sleep much longer on weekends or on a vacation? Most persons who are sleep-deprived attempt to make up for the lost sleep by "sleeping in" on weekends or during vacations. They often report less sleepiness after obtaining the additional sleep. Persons who are chronically sleep-deprived should be counseled regarding the importance of regular sleep and of obtaining at least 7 to 8 hours of sleep per night.

Since most persons must be up at a certain time in the morning, it is generally recommended that patients plan to add the extra needed sleep to the beginning of their sleep time. Most patients need to be advised that this will mean giving up certain enjoyable evening activities, such as late-night television and computer use. In addition, obtaining an extra hour or two of sleep on the weekends (when possible) is highly recommended.

In summary, patients who have symptoms consistent with a major sleep disorder, such as OSAHS or narcolepsy, should be referred to a sleep center. Patients who have symptoms consistent with drug effects or chronically insufficient sleep can be counseled initially by their primary care physicians. If a medication change or additional sleep does not improve the daytime sleepiness, referral to a sleep specialist is recommended.


1. Breslau N, Roth T, Rosenthal L, Andreski P. Daytime sleepiness: an epidemiological study of young adults. Am J Public Health. 1997;87:1649-1653.
2. National Sleep Foundation. Sleepiness in America. Washington, DC: National Sleep Foundation; 1997.
3. National Sleep Foundation. 1998 Omnibus Sleep in America Poll. Washington, DC: National Sleep Foundation; 1998.
4. Carskadon MA, Dement WC. Nocturnal determinants of daytime sleepiness. Sleep. 1982;5(suppl 2):S73-S81.
5. National Sleep Foundation. Sleep in America: 1995. Washington, DC: National Sleep Foundation; 1995.
6. Richardson GS, Carskadon MA, Orav EJ, Dement WC. Circadian variation of sleep tendency in elderly and young adult subjects. Sleep. 1982;5(suppl 2):S82-S94.
7. Schweitzer PK. Drugs that disturb sleep and wakefulness. In: Kryger MH, Roth T, Dement WC, eds. Principles and Practice of Sleep Medicine. Philadelphia: WB Saunders Co; 2000:441-461.
8. Espana RA, Scammell TE. Sleep neurobiology for the clinician. Sleep. 2004;27:811-820.
9. Carskadon MA, Dement WC. The multiple sleep latency test: what does it measure? Sleep. 1982;5(suppl 2):S67-S72.
10. Thorpy MJ. The clinical use of the Multiple Sleep Latency Test. The Standards of Practice Committee of the American Sleep Disorders Association. Sleep. 1992;15:268-276.
11. Zwyghuizen-Doorenbos A, Roehrs TA, Lipschutz L, et al. Effects of caffeine on alertness. Psychopharmacology (Berl). 1990;100:36-39.
12. Engleman HM, Martin SE, Kingshott RN, et al. Randomised placebo controlled trial of daytime function after continuous positive airway pressure (CPAP) therapy for the sleep apnoea/hypopnoea syndrome. Thorax. 1998; 53:341-345.
13. Doghramji K, Mitler MM, Sangal RB, et al. A normative study of the maintenance of wakefulness test (MWT). Electroencephalogr Clin Neurophysiol. 1997;103:554-562.
14. Banks S, Barnes M, Tarquinio N, et al. The maintenance of wakefulness test in normal healthy subjects. Sleep. 2004;27:799-802.
15. Broughton RJ, Fleming JA, George CF, et al. Randomized, double-blind, placebo-controlled crossover trial of modafinil in the treatment of excessive daytime sleepiness in narcolepsy. Neurology. 1997;49:444-451.
16. Johns MW. Daytime sleepiness, snoring, and obstructive sleep apnea. The Epworth Sleepiness Scale. Chest. 1993;103:30-36.
17. Johns MW. Reliability and factor analysis of the Epworth Sleepiness Scale. Sleep. 1992; 15:376-381.
19. Punjabi NM, Bandeen-Roche K, Young T. Predictors of objective sleep tendency in the general population. Sleep. 2003;26:678-683.
20. Chervin RD, Aldrich MS. The Epworth Sleepiness Scale may not reflect objective measures of sleepiness or sleep apnea. Neurology. 1999;52:125-131.
21. Engleman HM, Kingshott RN, Wraith PK, et al. Randomized placebo-controlled crossover trial of continuous positive airway pressure for mild sleep apnea/hypopnea syndrome. Am J Respir Crit Care Med. 1999;159:461-467.
22. Pack AI, Black JE, Schwartz JR, Matheson JK. Modafinil as adjunct therapy for daytime sleepiness in obstructive sleep apnea. Am J Respir Crit Care Med. 2001;164:1675-1681.
23. National Sleep Foundation. 2002 Sleep in America Poll. Washington, DC: National Sleep Foundation; 2002.
24. Flemons WW. Clinical practice. Obstructive sleep apnea. N Engl J Med. 2002;347:498-504.
25. Scammell TE. The neurobiology, diagnosis, and treatment of narcolepsy. Ann Neurol. 2003;53:154-166.
26. Choo KL, Guilleminault C. Narcolepsy and idiopathic hypersomnolence. Clin Chest Med. 1998;19:169-181.
27. Earley CJ. Clinical practice. Restless legs syndrome. N Engl J Med. 2003;348:2103-2109.
28. Dagan Y. Circadian rhythm sleep disorders (CRSD). Sleep Med Rev. 2002;6:45-54.
29. Akerstedt T. Shift work and disturbed sleep/wakefulness. Occup Med (Lond). 2003; 53:89-94.
30. Bassetti C, Aldrich MS. Idiopathic hypersomnia. A series of 42 patients. Brain. 1997; 120(pt 8):1423-1435.
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