Hypersomnia or hypersomnolence is also known as excessive daytime sleepiness. It is a neurological disorder that causes excessive sleepiness, distress, and problems with functioning. There are several subtypes of hypersomnia which is classified under sleep-wake disorders. The main presentation of hypersomnia in patients is prolonged nighttime sleep for a minimum period of 3 months. It is estimated that hypersomnia affects about 5 percent of the general population. However, there is a higher prevalence of hypersomnia in men due to the sleep apnea syndromes.
The symptoms of hypersomnia can be quantified using subjective scales such as the Epworth Sleepiness Scale or tests like the multiple sleep latency test (MSLT). Another scale that can be used to measure subjective sleepiness is the Stanford sleepiness scale. Once excessive daytime sleepiness is determined to be present, a full evaluation and complete medical examination is required to rule out other potential differential diagnosis. Hypersomnia can be divided into primary or secondary causes.
Hypersomnia Cause #1: Narcolepsy
Narcolepsy is a neurological disorder that is long term and results in a decreased ability to regulate the sleep and wake cycles. Patients often experience excessive daytime sleepiness that ranges from several seconds to minutes. These episodes can occur at any time. 70 percent of narcolepsy patients often experience sudden loss of muscle strength known as cataplexy that can be triggered by strong emotions. There can be inability to move or vivid hallucinations.
While patients with narcolepsy sleep the same number of hours as normal people, their quality of sleep is usually worse. The cause of narcolepsy is still unknown but there are several theories: where one suggests the low levels of neuropeptide orexin due to an autoimmune disorder, toxins, psychological stress, infections, and more.