Hypersomnia is characterized by recurrent episodes of excessive daytime sleepiness or prolonged nighttime sleep.
Persons with hypersomnia are compelled to nap repeatedly during the day, often at inappropriate times such as at work, during a meal or in conversation. These daytime naps usually provide no relief from symptoms. Patients often have difficulty waking from a long sleep, and may feel disoriented. Other symptoms may include anxiety, increased irritation, decreased energy, restlessness, slow thinking, slow speech, loss of appetite, hallucinations and memory difficulty. Some patients lose the ability to function in family, social, occupational or other settings.
Hypersomnia may be caused by drug or alcohol abuse, other sleep disorders such as narcolepsy or sleep apnea, or dysfunction of the autonomic nervous system. In some cases it results from a physical problem, such as a tumor, head trauma, or injury to the central nervous system. Certain medications, or medicine withdrawal, may also cause hypersomnia. Medical conditions including multiple sclerosis, depression, encephalitis, epilepsy or obesity may contribute to the disorder. Some people appear to have a genetic predisposition to hypersomnia; in others, there is no known cause. Hypersomnia typically affects adolescents and young adults.