Narcolepsy and other Hypersomnias
The terms “narcolepsy” and “hypersomnia” have both been used to describe conditions of excessive sleepiness during the day and greater need for sleep. Fatigue is distinguished from sleepiness, but at times people will use this term if the degree of tiredness felt is not truly associated with easily falling asleep during the day but rather a lack of energy and vitality.
Narcolepsy is associated with a chromosomal abnormality for the genes of the HLA system. It causes daytime sleepiness, difficulty getting up in the morning, sleep attacks (sudden need to sleep), sleep paralysis (inability to move on awakening), and dreamlike hallucinations when just falling into or awakening from sleep. In narcolepsy, the degree of sleepiness is variable among all patients, but either extra naps or stimulant therapies are almost always necessary for sustained functional activity. Untreated persons find it very difficult to maintain productive employment.
Cataplexy is a symptom of muscle laxity in about 50% of persons with narcolepsy. There is brief loss of muscle function in a few or most of the body muscles which occurs immediately after an emotional experience. Cataplexy can cause just facial droopiness after the person starts to laugh or at the other extreme, complete paralysis after a sudden surprise, excitement or embarrassment. It is always startling, and because it can cause total loss of control, cataplexy may cause great fear in the person experiencing it. The presence of true cataplexy is almost certainly an indication of narcolepsy.
Other types of hypersomnia include sleepiness associated with OSA when it is severe, pharmacologic side effects of certain medications, neurologic after effects of severe brain injuries including stroke or head injury, and as a symptom of psychologic or neurologic-degenerative diseases (bipolar depression and multiple sclerosis are examples). Finally, a fairly common hypersomnia is unassociated with narcolepsy or medical, neurologic or psychologic disturbances but causes profound sleepiness even with a long night time sleep period (so-called idiopathic hypersomnia).
First line therapy for all conditions causing somnolence is modafinil (Provigil). It is not an amphetamine, more accurately labeled a wakefulness promoting agent. Approval by insurance companies is sometimes withheld because of its expense, but modafinil is usually tried first for a majority of the disorders causing sleepiness. Side effects of headaches and occasionally jitteriness must be dealt with.
More severe sleepiness usually will call for amphetamine stimulants such as dextroamphetamine or methylphenidate, and combinations of two or three of these medications may needed at times. Judicious monitoring is required because the amphetamines, particularly the shorter acting ones, do have addictive potential. Side effects of amphetamines include palpitations, nervousness, and blood pressure elevation.
Persons with narcolepsy associated with cataplexy are sometimes greatly affected by the occurrence of cataplexy at inopportune times, but now there is approved treatment utilizing sodium oxybate at night. This medication has the added benefit of deepening sleep so that the daytime sleepiness is usually less severe when sodium oxybate is used.