There are a number of topics about sleep that are of particular concern to people with epilepsy. First, sleep disruption from any cause can be a reason for an increase in seizure frequency or severity. Second, sleep disruption can also have a negative effect on short-term memory, concentration, and mood. Seizures during the night can disrupt sleep, possibly resulting in further problems with memory and concentration the following day. Finally, various anticonvulsant drugs can affect sleep in both positive and negative ways.

The amount of rhythmic electrical activity normally occurring in the brain differs considerably between states of sleep and wakefulness. It is therefore not surprising that seizures (defined as sudden, abnormally rhythmic brain activity) can be affected by normal sleep states. Studies have shown that, overall, about 20% of seizures occur during sleep. Most sleep seizures begin during stage 2, with few beginning during slow wave sleep. These are times during which the electrical activity of the brain is more synchronized (rhythmic), which is why scientists believe that seizures are more likely to begin during these states. By contrast, few or no seizures begin during REM sleep, though it is not known why the state of REM sleep (occupying roughly one quarter of sleep time) appears to be protective against seizures.

The way seizures spread through the brain also seems to differ depending on sleep state. Interestingly, frontal lobe seizures begin during sleep more often than temporal lobe seizures. However, temporal lobe seizures are more likely to spread and result in a convulsion when beginning during sleep, while frontal lobe seizures are not. This intriguing finding could have implications for treatment if better understood.

Sleep Deprivation

Sleep deprivation, whether due to sleep disorders, nocturnal seizures, or simply not sleeping enough, has long been thought to increase the risk of seizures. In specific syndromes such as juvenile myoclonic epilepsy, this relationship can be quite dramatic to the point where seizures rarely or never happen when sufficient sleep is obtained. Sleep deprivation also increases the risk of partial seizures in many patients particularly when occurring frequently. This can be due to sleep disorders from outside influences like poor sleep hygiene, or because patients are busy and simply do not get enough sleep. Any of these influences can result in increased seizures, further disrupting the already limited sleep time, and leading to a vicious cycle of sleep disruption and intractable seizures. In this scenario, seizures are not likely to be controlled unless the sleep disruption is also resolved.

Finally, certain circadian rhythms may influence seizures independently of sleep. Patients with intractable temporal lobe epilepsy show abnormal secretion of melatonin, a sleep related hormone with a characteristic circadian pattern. Taking supplemental melatonin has been shown to help control seizures in a few small studies, raising the possibility that it may be useful in the treatment of some patients. However, further research is needed to know which patients are most likely to benefit.

Topic Editor: Carl Bazil, M.D.
Last Reviewed:10/01/05