Hypersomnia

Hypersomnia is the cardinal symptom of sleep disorders characterized by excessive daytime sleepiness, often resulting in increased sleep time or involuntary dozing. While insufficient sleep is the most common cause of excessive sleepiness, narcolepsy, circadian rhythm sleep disorders, sleep disordered breathing, insomnia, and medication effects are also implicated. The cause of hypersomnia can often be identified with a detailed clinical history, particularly noting comorbid systemic diseases or medications that may be contributing. Patients should be asked about sleep habits and schedules, what happens during the sleep period, and time periods they feel most awake and sleepy. It can be helpful to get collateral information from a family member or friend. An overnight polysomnogram (PSG) may be useful to diagnose sleep-disordered breathing or periodic limb movement disorder, and a daytime multiple sleep latency test (MSLT) can be done to objectively assess the degree of sleepiness in order to identify narcolepsy.

A.

Insufficient sleep syndrome presents with daytime sleepiness due to chronic partial sleep deprivation. A typical patient sleeps less than 6 hours per night. Diagnosis can usually be made based on clinical history alone. An increase in total sleep time to at least 7–8 hours per night should be recommended.
B.

Obstructive sleep apnea (OSA) is due to a recurrent collapse of the upper airway during sleep that is either partial (hypopnea) or complete (apnea). The severity of sleep apnea is defined by the apnea-hypopnea index (AHI), which is the number of times per hour of sleep that a respiratory event is present. An AHI < 5 is considered to be normal, 5–14 mild, 15–30 moderate, and > 30 indicates severe OSA. A sleep study, either overnight PSG or a home sleep apnea test, is needed to make a diagnosis of sleep apnea. Treatment options for OSA include weight loss, positional therapy, positive airway pressure (PAP) therapy, oral appliance therapy, and hypoglossal nerve stimulation. Patients with OSA who remain sleepy despite regular and effective use of PAP may benefit from alerting medications such as modafinil.
C.

Periodic limb movement disorder (PLMD) is characterized by stereotyped leg movements during sleep that disturb sleep and thus cause daytime sleepiness. Periodic limb movements can be identified by PSG. A periodic limb movement frequency of > 15 per hour of sleep suggests the diagnosis of PLMD. Treatment options include benzodiazepines, dopamine D2 agonists, alpha 2 delta ligands (e.g., gabapentin), and muscle relaxants. Asymptomatic periodic limb movements during sleep are common and do not require treatment.
D.

Recurrent hypersomnia (also known as Kleine-Levin syndrome) is characterized by periods of excessive sleeping up to 20 hours a day, which lasts from 2–35 days. Between hypersomnia episodes, the patient is cognitively normal and not sleepy. Treatment options (all of limited utility) include stimulants and chronic lithium carbonate to prevent onset of a hypersomnia episode. Recurrent hypersomnia can be encountered in some women in association with menses.
E.

Narcolepsy is associated with excessive daytime sleepiness, cataplexy, paralysis and hallucinations on sleep/wake transitions, and nocturnal sleep fragmentation. Cataplexy is the inappropriate loss of muscle tone with preservation of consciousness, which is triggered by a strong emotion, such as laughter; it is a feature of type 1 narcolepsy, but is absent in type 2 narcolepsy. Diagnosis of narcolepsy requires a positive MSLT: mean sleep latency (MSL) ≤ 8 minutes with two or more sleep onset rapid eye movement periods (SOREMPs). Treatment options directed at hypersomnolence include good sleep hygiene, scheduled short naps, daytime stimulants, and nighttime sodium oxybate. Sodium oxybate treats cataplexy in addition to sleepiness. Other treatment options for cataplexy include tricyclic antidepressants, selective serotonin reuptake inhibitors, and selective norepinephrine reuptake inhibitors
F.

Idiopathic hypersomnia consists of excessive daytime sleepiness that is not explained by another sleep or medical disorder. MSLT shows an MSL ≤ 8 minutes and less than two SOREMPs. Treatment options include good sleep hygiene, short scheduled naps, or stimulants.
G.

Delayed sleep phase syndrome is a circadian rhythm disorder characterized by habitual sleep and wake times that are delayed by at least 2 hours from the socially acceptable sleep period, resulting in sleep deprivation and subsequent daytime dysfunction. When these individuals are able to sleep on their preferred diurnal schedule, sleep deprivation does not occur and they do not experience daytime sleepiness. This sleep disorder is common in adolescents and young adults. Treatment can be either (1) phase delay with chronotherapy (delay sleep and wake times by 3 hours every day until the desired sleep and wake times are achieved), or (2) phase advance with melatonin in the evening and bright light exposure in the morning. Other circadian rhythm sleep disorders (e.g., shift work sleep disorder, jet lag, advanced sleep phase syndrome, non–24-hour sleep-wake disorder) can also be associated with daytime sleepiness.