Serotonin is one of the most important brain chemicals, or neurotransmitters, for regulating the sleep/wake cycle. Diets high in the amino acid tryptophan can maintain healthy serotonin levels, but lifestyle choices like constant travel and an erratic sleep schedule can disrupt serotonin production. When serotonin levels are not normal, sleep disturbances and other issues can result, including depression and chronic fatigue syndrome.
Role in Sleep Cycle
Even in the 21st century, sleep is not fully understood. However, serotonin plays a definite role in sleep cycles, as high levels of serotonin are associated with wakefulness and lower levels with sleep. Serotonin also is synthesized by the pineal gland to make melatonin, the hormone that is directly related to healthy sleep. When melatonin is taken as a dietary supplement, it helps people with sleep disorders get to sleep more quickly, according to the U.S. Department of Health and Human Services. However, excess melatonin levels can also lead to trouble sleeping and other health issues.
Role in Dream Formation
While serotonin levels are lower in sleep than while awake, they are at their lowest during REM sleep, also known as dreaming sleep. In effect, neurons with serotonin receptors are active during all stages of sleep until REM, so they appear to act as a "REM inhibitor" most of the time, as reported by "Sleep Research Online" in 1999. When serotonin levels drop, the neurotransmitter acetylocholine rises in the brain. This is why many anti-depressants reduce dreaming sleep, because increasing serotonin levels inhibit the rise of acetylocholine, according to sleep scientist James Pagel in his book "The Limits of Dream."
Role in Sleep Disruption
Low serotonin levels result in sleep disruption and sleep disorders, including insomnia. Stress is a common cause of low serotonin levels, resulting in a snowballing feedback cycle of disrupted sleep, depression, anxiety and fatigue during the day, according to clinical psychologist Joseph M. Carver. You can give your sleep life a jump-start by eating foods high in tryptophan, a precursor to serotonin, as well as by getting daily exercise. In general, high-carbohydrate foods like potatoes and grains have tryptophan, as do most cheeses and meats. Mindfulness practices such as meditation and yoga are also linked to higher levels of serotonin. While high levels of serotonin may lead to feelings of bliss and happiness, there can be too much of a good thing. Excess serotonin levels are toxic to the brain, and can lead to a condition known as "serotonin syndrome."