The Effect of Light on the Body's Melatonin Levels
 When our bodies don't make enough melatonin, it hinders our ability to sleep. Melatonin is normally made by the human body's pineal gland -- a pea-size gland situated above the middle of the brain that is inactive during the day. When the sun goes down and darkness occurs, the pineal is "turned on" and begins to produce melatonin. Subsequently, sleepiness occurs. The flow of melatonin coincides with lightness and darkness, and can also be affected by electromagnetic energy and artificial light.
Humans are exposed to much more light than they used to be with the expansion of artificial lighting systems. This artificial light reduces the amount of time humans are exposed to darkness to about eight hours per day throughout the year. It is important to strike a healthy balance between light and dark exposure, as too little light can inhibit the production of melatonin while over-illumination can also reduce melatonin levels.
Some of the side effects of low melatonin levels include:
- Inability to sleep
- Lack of dreaming
- High stress levels
- Depression
- Elevated cholesterol and blood pressure
- Unusual feeling of anxiety
Since light plays an integral role in the production of melatonin, people who take night jobs may have an especially hard time adjusting to daytime sleep and could experience short-term insomnia. The cycle can also account for some jet lag. Taking supplemental melatonin may help advance or delay the sleep/wake cycle, and its effect can last up to 6 hours.
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