Brighter Days Invite a Better Night’s Sleep

DO YOU have trouble sleeping? The problem could be a lack of exposure to bright light during the day, especially if you are elderly. Researchers in Japan recently conducted a study of nursing-home residents who suffered from insomnia, and they found that the poor quality of the subjects’ sleep was related to their limited daily exposure to environmental light. At the same time, blood tests revealed that these elderly residents had low levels of the hormone melatonin.

Melatonin is secreted by the pineal gland in the brain. Under normal circumstances, the daily rhythm of melatonin secretion causes concentrations in the blood to be “high during the nighttime and nearly undetectable during the daytime,” says the report in The Journal of Clinical Endocrinology & Metabolism. However, when the elderly are not exposed to enough light during the day, blood melatonin levels fall. It seems that as far as the body is concerned, this blurs the distinction between day and night, which the researchers believe affects sleep quality.

When the elderly insomniacs were exposed to four hours of bright artificial light near the middle of the day (ten o’clock to noon and two o’clock to four) for four weeks, their melatonin secretion rose “to levels similar to those in the young control group,” says the report. * At the same time, their sleep quality improved.

These findings led the researchers to “assume that elderly persons, especially EIs [elderly insomniacs], spending most of their daily life under room light, could receive insufficient light intensity to adjust their circadian timing system [their body’s internal clock].” Because some elderly people take melatonin supplements as a sleeping aid, the report observes: “Considering possible side effects of long-term melatonin administration, exposure to midday light may provide a more desirable, potent, safe, and self-directed therapeutic tool for EIs with diminished melatonin secretion.”

So if you are indoors most of the day and suffer from insomnia, why not try to spend a little more time outside​—or at least let as much light as possible into your home during the day, and keep your bedroom dark at night. You may find that brighter days invite a better night’s sleep.

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