Melatonin

Have a restful sleep

A key factor in how human sleep is regulated is exposure to light or to darkness. Exposure to light stimulates a nerve pathway from the retina in the eye to an area in the brain called the hypothala-mus. There, a special center called the supra-chiasmatic nucleus (SCN) initiates signals to other parts of the brain that control hormones, body temperature and other functions that play a role in making us feel sleepy or wide awake. The SCN works like a clock that sets off a regulated pattern of activities that affect the entire body. Once exposed to the first light each day, the clock in the SCN begins performing functions like raising body temperature and releasing stimulating hormones like cortisol. The SCN also delays the release of other hormones like melatonin, which is associated with sleep onset, until many hours later when darkness arrives. Melatonin is a natural hormone made by your body's pineal (pih-knee-uhl) gland. This is a pea-sized gland located just above the middle of the brain. During the day the pineal is inactive. When the sun goes down and darkness occurs, the pineal is "turned on" by the SCN and begins to actively produce melatonin, which is released into the blood. Usually, this occurs around 9 pm. As a result, melatonin levels in the blood rise sharply and you begin to feel less alert. Sleep becomes more inviting. Melatonin levels in the blood stay elevated for about 12 hours - all through the night - before the light of a new day when they fall back to low daytime levels by about 9 am. Daytime levels of melatonin are barely detectable.

For melatonin to be helpful, the correct dosage, method and time of day it is taken must be appropriate to the sleep problem. Taking it at the "wrong" time of day may reset your biological clock in an undesirable direction. Some studies show promise for the use of melatonin in shortening the time it takes to fall asleep and reducing the number of awakenings, but not necessarily total sleep time.

Shift Workers

Melatonin might help shift workers on irregular shifts who need to adjust their schedules. When taken in low doses at the appropriate time, melatonin can help advance or delay the sleep-wake cycle. The effect can last for six hours. When taken in the morning, it may cause fatigue and reduced reaction time, reduced vigilance and decreased vigor during the day.

Jet Lag

When traveling across time zones, we need to adjust our body clocks from "home time" to the new time. The more time zones we cross, the longer it takes to reset the body clock to the new time. After arriving from a long trip, our body clocks are out of synch with the local time and we feel sleepy, alert and hungry at the wrong times. The problem is compounded by sleep loss during an overnight flight and possibly by alcohol and caffeine consumed on board. These add up to produce "jet lag." The use of melatonin for jet lag appears reasonable. Many published scientific studies conclude that melatonin can be effective for preventing or reducing jet lag, particularly for crossing five or more time zones and when traveling east.

Delayed Sleep Phase Syndrome

People with Delayed Sleep Phase Syndrome (DSPS) are only able to fall asleep late into the night or early in the morning. Although rare in adults, the syndrome is quite common among adolescents. Several studies suggest that melatonin may be of help for this condition.