hypersomnia

Hypersomnia is a sleep disorder characterized by excessive daytime sleepiness and prolonged nighttime sleep that is not restorative. It can be a symptom of other medical conditions like sleep apnea or depression, or it can arise spontaneously.1

Primary forms of hypersomnia include narcolepsy with cataplexy, which involves sudden muscle tone loss, and idiopathic hypersomnia, where the cause is unknown. Narcolepsy is linked to abnormal functioning in brain regions that regulate sleep, particularly involving the hypocretin molecule. Symptoms can also include vivid hallucinations and sleep paralysis.12

Some hypersomnia cases are periodic, like Kleine-Levin syndrome, which features episodes of excessive sleep lasting days or weeks, accompanied by increased appetite and behavioral changes. While the exact mechanisms are still being researched, disruptions in sleep-wake regulation are believed to be involved.2