Proteins and/or complex carbohydrates plus zinc release the amino acid tryptophan which our bodies (with enough B6, Magnesium, Zinc and sunlight) convert to the neurotransmitter serotonin which is then converted (with more B6, magnesium and darkness) to the sleep-inducing hormone melatonin.
Serotonin is a neurotransmitter that helps regulate a lot of your bodily functions. Along with melatonin, serotonin is especially involved in your sleep cycle. Melatonin helps you fall asleep, while serotonin helps you wake up feeling refreshed. At least, that's what serotonin and melatonin do in people who are fortunate enough to have the right amount.
News Note: No Aspartame
There are many reasons to avoid the artificial sweetener aspartame, which I'll cover in a future article, but when it comes to your ability to sleep, aspartame contains phenylalanine, an amino acid that competes with tryptophan for absorption. If phenylalanine levels are reduced, more tryptophan will be available for production of serotonin, then into melatonin and blessed sleep.
Serotonin
Serotonin is a hormone that acts as a neurotransmitter in the brain and in the gut. (Medicine.net defines a hormone as a chemical substance produced in the body that controls and regulates the activity of certain cells or organs.) 95% of the body's serotonin is produced in the gut where it regulates the digestive process. The remaining 5% of the serotonin is produced in blood platelets (where it controls vasoconstriction and blood clotting), and in the brain (from the amino acid L-tryptophan conversion into 5-HTP which then crosses the blood-brain barrier to become serotonin).
Serotonin levels in the brain have widespread and often profound implications, including a role in sleep, appetite, memory, learning, temperature regulation, mood, sexual behavior, cardiovascular function, muscle contraction, and endocrine regulation. Not only does this hormone control physiological aspects of the body, but it also has an involvement in behaviors like eating, sleeping and aggression.
Low Serotonin Levels
Serotonin is implicated in a broad range of serotonin disorders like depression, schizophrenia, and Parkinson's disease. Serotonin deficiencies have been one of the factors to blame for ailments such as anorexia, bulimia, obsessive compulsive disorders, migraines, social phobias, schizophrenia and possibly SIDS (Sudden Infant Death Syndrome).
There are many reasons you can suffer lowered levels of serotonin; stress, lack of sleep, lack of exercise, poor nutrition, and lack of sunlight. Lowered levels of serotonin are suspected as a cause for ADD, irritability, depression, aggression, anxiety, lack of concentration, chronic pain, restlessness or fatigue, nausea, obsessive-compulsive disorder, weight gain or loss, fibromyalgia, arthritis, chronic fatigue syndrome, heat intolerance and other syndromes. Fluctuating serotonin levels are suspected in bipolar disorder (manic depression). You don't have to feel depressed or anxious; symptoms may be purely physical.
Serotonin's Role as a Modulator
Dr. Barbara S. Beltz, a professor of neuroscience at Wellesley College, Wellesley, Mass., refers to serotonin as a modulator. "It has widespread functions in 'setting the gain' of a variety of areas in the brain and nervous system. You can think of serotonin as a volume control in the brain and nervous system."
According to Dr. Beltz, other neurotransmitters allow communication between two neurons. Serotonin actually alters the efficiency and efficacy of communication between neurons that may use a variety of other chemicals as their primary neurotransmitter.
Fairness
Serotonin also affects our feelings of "fairness". UCLA scientists reported that the human brain responds to being treated fairly the same way it responds to winning money and eating chocolate; being treated fairly turns on the brain's reward circuitry. In the new Science study, they and their Cambridge colleagues report that people with low serotonin levels were found to be more sensitive to being treated unfairly.
"The same person may experience the same thing as fair and unfair on different days based on how the neurochemistry of the brain is functioning," said study co-author Matthew D. Lieberman, UCLA associate professor of psychology and a founder of social cognitive neuroscience. "When we feel something is unfair, that may have to do with how our brain causes us to experience the world. Our subjects are not aware their serotonin levels are affecting the way they experience the world. This suggests we should be more forgiving of other people's perspectives."
"A sense of fair play is not a purely rational process," he added. "It seems not to be the case that, like a math formula, if something is fair, it's fair for all time, in all situations."
Melatonin
Circadian rhythm
In humans, melatonin is produced by the pineal gland, a gland about the size of a pea, located in the center of the brain but outside the blood-brain barrier. The melatonin signal forms part of the system that regulates the sleep-wake cycle by chemically causing drowsiness and lowering the body temperature.
Infants' melatonin levels become regular in about the third month after birth, with the highest levels measured between midnight and 8 AM.
Light Dependence
Production of melatonin by the pineal gland is inhibited by light and permitted by darkness. For this reason melatonin has been called "the hormone of darkness" and its onset each evening is called the Dim-Light Melatonin Onset (DLMO). Secretion of melatonin as well as its level in the blood, peaks in the middle of the night, and gradually falls during the second half of the night, with normal variations in timing according to whether the individual is more alert in the morning or later in the day.
Until recent history, humans in temperate climates were exposed to only about six hours of daylight in the winter. In the modern world, artificial lighting reduces darkness exposure to typically eight or fewer hours per day all year round. Even low light levels inhibit melatonin production to some extent, but over-illumination can create significant reduction in melatonin production.
Recently, my oldest daughter purchased a light box to help with her photography. She added more and more lamps to the box to increase the illumination. She had started the project at 10:30 p.m. intending to work for only an hour. She found herself staying up past 3 a.m. - surprised because she wasn't tired. The extremely bright lights had increased her serotonin levels, making her feel good AND insuring that the serotonin wouldn't be converted to sleep-inducing melatonin. Unfortunately, she paid dearly for the sleep deprivation the next day.
Antioxidant
Besides its function as synchronizer of the biological clock, melatonin also exerts a powerful antioxidant activity. Melatonin's capacity to absorb free radicals extends up to 10X the amount of other, conventional antioxidants.
In animal models, melatonin has been demonstrated to prevent the damage to DNA by some carcinogens, stopping the mechanism by which they cause cancer. It also has been found to be effective in protecting against brain injury caused by lack of oxygen in newborn rats. Melatonin's antioxidant activity may reduce damage caused by some types of Parkinson's disease, may play a role in preventing cardiac arrhythmia and may increase longevity; it has been shown to increase the average life span of mice by 20% in some studies.
Learning, Memory and Alzheimer's
Melatonin receptors appear to be important in mechanisms of learning and memory in mice, and melatonin can alter electro-chemical processes associated with memory. The first published evidence that melatonin may be useful in Alzheimer's disease was the demonstration that this neurohormone prevents neuronal death caused by exposure to the amyloid beta protein, a neurotoxic substance that accumulates in the brains of patients with the disorder. Melatonin also inhibits the clumping of the amyloid beta protein into neurotoxic microaggregates which seem to underlie the neurotoxicity of this protein, causing death of neurons and formation of neurofibrillary tangles, the other landmark of Alzheimer's disease.
Mood disorders
Melatonin has been shown to be effective in treating seasonal affective disorder (SAD), and is being considered for bipolar and other disorders where circadian disturbances are involved. It has been observed that bipolar disorder might have, as a "trait marker" (something which is characteristic of being bipolar, that does not change with state), supersensitivity to light, i.e. a greater decrease in melatonin secretion in response to light exposure at night.
Cancer
A systematic review of clinical trials involving a total of 643 cancer patients using melatonin found a reduced incidence of death. Melatonin levels at night are reduced to 50% by exposure to a low-level incandescent bulb for only 39 minutes, and it has been shown that women with the brightest bedrooms have an increased risk for breast cancer. Reduced melatonin production has been proposed as a likely factor in the significantly higher cancer rates in night workers.
Now What?
So, now that we know that higher levels of serotonin and melatonin are desirable, and lower levels can do all sorts of bad things to our bodies, how do we actually put all this information to use so we can sleep at night?
Next: Putting it All Together
The Insomnia Series
Falling asleep naturally Part 1
Falling asleep naturally Part 2: The Interaction of Biochemicals
Falling asleep naturally Part 3: Tryptophan and Insulin
Falling asleep naturally Part 4: Complex vs Simple Carbohydrates
Falling asleep naturally Part 5: Serotonin and Melatonin
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