As of 2015, the cause of excessive daytime sleepiness is not known; however, studies indicate that low levels of hypocretin, a neurochemical that helps control sleep and awake cycles, may be the major cause of the disorder, according to Mayo Clinic. Research suggests that the disorder may be genetic. Certain medications, including stimulants, tricyclic antidepressants and sodium oxybate, may treat excessive daytime drowsiness.
Although the exact cause of low levels of hypocretin is unknown, research shows that people with cataplexy are likely to suffer from excessive daytime drowsiness, explains Mayo Clinic. Cataplexy is an unexpected loss of muscle tone that leads to body weakness. Unconfirmed studies indicate that the H1N1 virus and treatments for the virus may cause the problem. The sleep cycle generally begins with nonrapid eye movement sleep, then proceeds to rapid eye movement sleep. However, the process of falling asleep in people with excessive sleepiness begins with REM. Symptoms include hallucinations, sleep paralysis and cataplexy.
Modafinil, armodafinil, amphetamines and methylphenidate stimulate the central nervous system and make patients stay awake, explains Mayo Clinic. Tricyclic antidepressants that help reverse cataplexy include clomipramine, protriptyline and imipramine. Selective serotonin reuptake inhibitors and serotonin and norepinephrine reuptake inhibitors may also counteract the problem. Studies on hypocretin gene therapy, immunotherapy and hypocretin replacement are ongoing to identify further treatments. People with excessive daytime sleepiness should exercise often, take short naps and use the same schedule to sleep and wake up every day..