Sleep - Melatonin and Sunlight

What makes us sleep?

If you were to ask almost any group of individuals this question you'd likely get a variety of answers. Some people might say a comfortable bed and quiet surroundings are what makes us sleep. Others would quite rationally explain that a nightcap is needed. Sheer exhaustion, a full belly, and someone to snuggle with are some of the other opinions people have about what makes us sleep.

Interestingly, few people know that the correct answer to the question is actually the release of the hormone, melatonin.

Melatonin is a hormone that is secreted by the pineal gland, which is located at the base of the brain. It is secreted at varying levels throughout the day and it helps to regulate the body's sleep-wake cycle. The pineal gland helps regulate the body's internal clock, and helps keep the body in balance by regulating the release of different hormones, neurotransmitters and chemicals that affect the body in many ways.

In fact, there is a high correlation between the release of melatonin and the body's temperature, both of which are controlled by the body's circadian rhythm. Melatonin levels, and body temperature, are normally low during the day and gradually increase as evening arrives. Both reach their highest levels during nighttime sleep.

The onset of darkness stimulates the pineal gland into action which is why melatonin levels remain low during daylight hours. During the day, the melatonin levels are barely traceable. As darkness arrives, the pineal gland starts releasing more melatonin into the bloodstream. As more melatonin travels throughout the blood, the body starts getting more and more tired. Blood pressure slows as the body prepares to fall asleep. Melatonin levels continue to increase until they peak which generally occurs around 3 or 4 a.m. Afterwards, as melatonin levels slowly begin to subside, the body prepares to be awakened. 

Anything that disrupts the normal release of melatonin can also disrupt sleep patterns. The body knows that the presence of less melatonin means that it should be alert and awake and ready for the day. Increased melatonin production signals that it is time to go back to sleep. Therefore, darkness any time of day can trigger the release of melatonin and the changes that naturally take place with its release.

The weather can have a direct effect on the production of melatonin, especially on overcast days or during the winter months with fewer hours of sunlight. Working inside a windowless office that lacks suitable artificial lighting can also cause problems for melatonin production. Such scenarios can cause melatonin levels to remain higher than normal during daytime, and may cause a person to feel less energetic and drowsy when he otherwise should feel alert and be able to concentrate. When more melatonin is released throughout the day, less will be released during the night, and this imbalance can cause insomnia and other sleeping disorders.

Light Therapy can help when natural sunlight isn't available. However the best way to keep melatonin levels balanced is by allowing natural sunlight to penetrate your skin.