Having the TV or a light on when you're trying to go to sleep is more than just distracting. Both c...
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Having the TV or a light on when you're trying to go to sleep is more than just distracting. Both can actually affect what has been called ``the hormone of darkness.'' This hormone, called melatonin, is involved in your daily biological cycles, including your sleep cycle and patterns of sleeping and waking. Melatonin is produced by a small, pine-cone shaped gland deep in middle of the brain called the pineal gland. When the pineal gland is producing a lot of melatonin and blood levels of the hormone are high, you feel sleepy and your body temperature lowers to prepare for sleep. The pineal gland keeps secreting melatonin based on what your body perceives as the length of night. So blood levels of melatonin are low during the daylight hours and peak during the dark. And this is based on the amount of light hitting the retina of your eye. Light on the retina sends a signal to a part of the brain called the hypothalamus, which coordinates the signals of your biological clock. When light is hitting the back of your eyes, the hypothalamus signals the pineal to stop releasing melatonin. You wake up and your body temperature starts to rise. A dark room helps you to sleep because it increases melatonin production.

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