By the mid-1800s, artificial light was part of just about everyone’s life. The advent of the light bulb and the burgeoning city nightlife sped up the exchange of ideas and money, but it also affected our bodies and minds in ways that few historians thought to record at the time. Here’s a look at three ways lighting can affect your physiology and why your body might enjoy a break from the bulbs.
Melatonin is a hormone that is mostly produced in the absence of light. It is secreted by the pineal gland as part of your natural sleep cycle, and is known to inhibit tumor growth among many other functions. Sleeping with the lights on causes a drop in melatonin and sets the conditions for tumors to spread. Light exposure has been linked to increased breast cancer rates in female night-shift workers, and may be a factor in higher cancer rates in industrialized nations than developing nations.
Regulating Menstrual Cycles
The pineal gland’s preference for darkness also affects female fertility and the menstrual cycle. Some researhcers theorize that moonlight affects melatonin secretion, which in turn affects the delivery of prolactin, a hormone related to lactation and sexual satisfaction. This connection between moonlight and fertility inspired Lunaception, the practice of mimicking moon cycles with sleep-time lighting, as a way to regulate periods and predict ovulation.
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Regulating Your Sleep Cycle
Your circadian rhythm, or body clock, runs on the light-dark cycle. Indoor electric lighting can have a phase-delaying effect on your body, pushing your sleep schedule later and possibly displacing healthy sun exposure. Delayed sleep onset when you have to work on a day schedule can rack up a huge sleep debt that affects mood and performance at work and school. The Lighting Research Center offers studies detailing the effects of light on alertness, sleep schedule and hormone production.
It seems our bodies have yet to adjust to the luminous 24-hour cityscape many of us know today. Considering that artificial light stimulates non-visual systems like hormones, fertility and the sleep-wake cycle, it might be worth it to cut your exposure to TVs and computers a few hours before bed-time and enjoy your shut-eye in total darkness. A happy pineal gland pays off for your body, mind and soul.
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