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Why do we get sleepy in the evening, and wake up in the morning? The answer is “light cues.” Nerve signals from the eye travel into the depth of the brain, and synchronize our feelings of tiredness and wakefulness with the rhythm of light and dark. The hormone melatonin plays a significant role in this process.

Blind people frequently have trouble going to sleep when other people do. In the absence of light cues, their sleep/wakefulness cycle runs “free,” independent of day and night transitions. A blind person’s typical sleep/wake cycle lasts slightly longer than 24 hours, and therefore slowly marches around the clock. Consequently, a blind person may eventually feel like going to bed at noon, and waking up at midnight.

This is one of the lesser-known challenges of being blind, and one that can be quite burdensome. A recent small double-blind placebo-controlled crossover trial suggests that melatonin taken orally can help.1

In this study, researchers found that melatonin at a dose of 10 mg nightly (taken an hour before bedtime) can restore normal sleep/wake cycles in most participants. Once this high dose had taken effect, a much smaller dose of 0.5 mg nightly was enough to maintain normal sleep rhythms.

While these findings are promising, larger and longer studies are necessary to fully prove that melatonin can help blind people sleep.