Room light before bedtime suppresses melatonin


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An interesting study just appeared in the Journal of Clinical Endocrinology & Metabolism that adds to two earlier posts my blog — one about circadian rhythms and the role of melatonin in regulating sleep and overcoming jet lag, the other about the use of “light visors” at appropriate times to help reset sleep cycles. The new study, from Harvard, found that ordinary electric light before bedtime strongly suppresses melatonin production.

Backtracking for a moment:

Melatonin is a hormone produced at night by the pineal gland in the brain. In addition to its role in regulating the sleep-wake cycle, melatonin has been shown to lower blood pressure and body temperature and has also been explored as a treatment option for insomnia, hypertension and cancer.

As a result, many people take melatonin at bedtime after flying from west to east, to help move their sleep cycle forward. And some people, including top athletes at the Commonwealth Games, use the light visors I discussed in that previous post to suppress melatonin in the morning (if they flew west to east) or the evening (if they flew east to west).

This all makes intuitive sense, but as far as I know most people had assumed that ordinary room lights wouldn’t have a significant effect on melatonin — otherwise, no one would shell out the big bucks for a light visor! So what does this mean? Well, if you have trouble getting to sleep, you might want to start paying more attention to your lighting environment in the hours before bedtime. And, on the plus side, if you’re travelling across time zones, you should be able to harness this effect just like a light visor!

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