Hypersomnia

I. Background
Hypersomnia, also known as excessive daytime sleepiness (EDS), is defined by a need to sleep during daytime hours and the ability to fall asleep in situations during which alertness is desired (1). EDS should be differentiated from generalized fatigue and nonspecific tiredness, as patients often use the terms interchangeably. Generalized fatigue is a problem of decreased physical energy, muscle exhaustion, and possibly poor concentration and memory, whereas hypersomnia is the problem of falling asleep at inappropriate or undesired times.
II. Pathophysiology
A. Etiology
Hypersomnia can be a primary sleep disorder, but is more commonly secondary to disorders that disrupt normal sleep patterns. Poor quality sleep may be caused by behavioral routines, environmental disturbances, medical and psychological disorders, or insomnia.
B. Epidemiology
EDS is a common problem, affecting between 5% and 15% of the general adult population (2), and as many as 58% of psychiatric patients (3). The prevalence of narcolepsy is thought to be approximately 0.05%, although epidemiologic studies vary greatly depending on the country of origin and the definitions of the disease.
III. Evaluation
The evaluation of hypersomnia should include an investigation for intrinsic, extrinsic, and circadian rhythm sleep disorders, as well as medical and diseases that are associated with sleepiness. Intrinsic causes of daytime sleepiness, including primary sleep disorders, are relatively uncommon as compared to extrinsic causes and circadian rhythm disorders (misalignment of sleep patterns with local time)(1).
A. History and review of systems
Generalized fatigue should be differentiated from daytime sleepiness in which one experiences head sagging, eyelid drooping, and short periods of sleep at inappropriate times (1). A history of sleep attacks (suddenly falling asleep in dangerous situations) or episodes of cataplexy (sudden and transient loss of muscle strength) can be particularly dangerous and highly suggestive of a diagnosis of narcolepsy (1,3). A full review of systems often highlights other medical and psychiatric disorders that may be causing daytime sleepiness. Abrupt symptom onset should heighten concern for central nervous system tumors and ischemic stroke.
  • Sleep patterns A thorough discussion of the patient's sleep pattern should include details about bedtime and wake time, nighttime awakenings, eating habits prior to sleep, work patterns, and the sleep behavior of bed partners and other members of the household.
  • Medication history Medications that induce somnolence or interrupt the normal sleep cycle are listed in Table 2.8.1.
B. Physical examination
The physical examination is most useful in the evaluation of medical and psychological disorders that may be causing sleepiness. Patients with intrinsic, extrinsic, and circadian rhythm sleep disorders are likely to have a normal physical examination.
TABLE 2.8.1 Substances That Can Cause Somnolence or Disordered Sleep
Pharmacologic agents Herbal agents
Tricyclic antidepressants Chamomile
Lithium Rosemary
α-1 and 2 antagonists Kava kava
Anticholinergics Marjoram
Anticonvulsants Poppy seeds
Antiemetics Valerian
Antihistamines Melatonin
Antiparkinsonian agents
Antipsychotics Other
Barbiturates Alcohol
Benzodiazepines Amphetamines
β-Blockers Nicotine
Clofibrate Illicit drugs
Decongestants
Gemfibrozil
Muscle relaxants
Opiates
Selective serotonin reuptake inhibitors
Spironolactone
Adapted from Qureshi A, Lee-Chiong T Jr. Medications and their effects on sleep. Med Clin North Am 2004;88(3): 751 - 766.
TABLE 2.8.2 Differential Diagnosis of Hypersomnia
Intrinsic disorders (1,2) Extrinsic disorders (2,4)
Narcolepsy with or without cataplexy
Posttraumatic hypersomnia
Obstructive sleep apnea
Restless legs syndrome
Periodic limb movement disorder
Parkinson's disease
Idiopathic hypersomnia		 Alcohol (decreases sleep latency and causes rebound arousal in the middle of the sleep cycle)
Environmental factors causing poor sleep (e.g., snoring spouse, loud noises)
Sleep deprivation
Circadian rhythm sleep disorders (3) Medical and psychiatric diagnoses (2)
Jet lag type
Delayed sleep phase type (more common in adolescents and young adults, usually very late bed times and late or midday wake times)
Advanced sleep phase type (more common in older adults, early bed time and early wake time)
Shift work type		 Alcoholism and substance abuse
Alzheimer's disease and other dementias
Anxiety disorders
Chronic obstructive pulmonary disease
Depressive disorders
Gastroesophageal reflux
Hypothyroidism
Menopausal symptoms, ‘hot flashes’
Obstructive sleep apnea
Panic disorders
Paroxysmal nocturnal dyspnea
Central nervous system abnormalities (rare)
C. Testing
Intrinsic sleep disorders are best evaluated using a multiple sleep latency test (MSLT) and/or an overnight polysomnograph (1,3). A sleep latency of <5 minutes is considered pathologic sleepiness (1,3). The polysomnogram can detect excessive limb movement, sleep disordered breathing, apnea, and hypoxia (1).
IV. Diagnosis
A. Differential diagnosis
The differential diagnosis for hypersomnia is listed in Table 2.8.2.
B. Clinical manifestations
Hypersomnia may present with significant fatigue, trouble with work or school performance, marital or relationship problems, accidents or personal injury (particularly with narcolepsy), and can be the first sign of dementia or other neurologic disorders.
References
1. Silber M, Krahn L, Morgenthaler T. Sleep medicine in clinical practice. London: Taylor & Francis, 2004.
2. Roth T, Kryger MH, Dement WC. Principles and practice of sleep medicine, 3rd ed. Philadelphia, PA: WB Saunders, 2000.
3. Doghramji K. Assessment of excessive sleepiness and insomnia as they relate to circadian rhythm sleep disorders. J Clin Psychiatry 2004;65(Suppl 16):17 - 22.
4. Qureshi A, Lee-Chiong T Jr. Medications and their effects on sleep. Med Clin North Am 2004;88(3):751 - 766.