What is Serotonin (roughly)?
Serotonin (5-Hydroxytryptamin (5-HT) or Enteramin) is a neurotransmitter that is primarily found in the central nervous system, the gastrointestinal tract and the blood. It is commonly known as a major contributor to feelings of well-being. Sometimes it is even called the “happiness hormone”. Interestingly about 95% of it is usually located in the the gut of which 90% are in the enterochromaffin cells where it is produced and regulates the intestinal movements. Most of the remainder is located in serotonergic neurons in the central nervous system and in the blood. Besides the regulation of intestinal movements it primarily regulates the tone of the blood vessels and signal transmission in the central nervous system.
How does serotonin influence sleep apnea?
Serotonin primarily affects the cardiovascular system, the gastrointestinal tract and the nervous system.
1. Effects on the cardiovascular system
Serotonin regulates the contraction and relaxation of blood vessels. In the lung and kidney the contraction effect is most immanent and in the blood vessels it is mostly the relaxation that dominates. It is known, that malfunctions in the cardiovascular system have a major affect on sleep apnea. It is certain, that a change in serotonin levels in the blood has a direct affect on sleep apnea.
2. Effects on the central nervous system
a. Moods, feelings of well-being
The best known effect of serotonin on the body is it’s influence on moods through the central nervous system. If the serotonin level in the brain is too high it can cause hallucinations and restlessness. Depressions are often connected to too-low levels of serotonin. In some cases anxiety and bad aggressive temper can be traced back to low levels of serotonin.
IMPORTANT: An increased intake of serotonin rich food like chocolate or banana does not affect the serotonin level in the brain. The uplifting effect is due to the high level of carbohydrates that lead to an increase in the production of neurotransmitters in the brain.
b. Sleep-Wake Cycle
Since the 1950’s it is known, that serotonin has a regulating effect on the sleep-wake cycle. However, the studies concerning the mechanisms of this regulatory effect have long been contradictory. Recent studies have shown, that serotonin primarily influences the wake periods through the activity of the serotonin containing neurons in the hypothalamus. During sleep this activity is reduced and almost stops during REM. An increase as well as a decrease in the serotonin level can cause disruptions in the sleep-wake cycle and therefore have a strong influence on the exposure to sleep apnea.
The nerves that control breathing need a certain amount of serotonin in order to do communicate with the brain. An improperly-working serotonin system deprives the body of an adequate supply of the neurotransmitter, often resulting in sleep apnea. Also, serotonin receptors control the release of hormones such as cortisol. One role of cortisol is to help control the muscles needed for breathing.
Following Dr. Murray, author of “5 HTP – The Natural Way to Overcome Depression, Obesity, and Insomnia” sleep apnea that can be at least partially traced back to a low serotonin level can be treated by using 5-HTP as part of their overall medical care.
The recommended dose is 100 to 300 mg of 5-HTP before bedtime. Dr. Murray reports that sleep apnea patients that take 5-HTP sleep more soundly.
On one hand this is great news, but it should be very clear, that the intake of 5-HTP can not cure sleep apnea alone. It will always have to be combined with a combination of other treatments that target obesity, breathing habits, lifestyle (alcohol/nicotine/narcotics) and so on. Please talk to your doctor before taking HTP-5 or other medication and also consider interactions of anti depressives and serotonin levels.