Wright et al., Curr. Biol., 2013
Fig. 3. Black upward triangles indicate start of melatonin release; red squares are melatonin midpoint; melatonin tapers off at blue downward triangles. Notice how melatonin release (and sleep) shifts later in electrical lighting. [Caption altered from original for clarity.]
Can night owls become early birds?
This is Sandra Tsing Loh with the Loh Down on Science.
Meet chronobiologists at the University of Colorado, Boulder. They study circadian rhythms, AKA body clocks. These control biological processes, like sleep, that occur every twenty-four hours.
See, our energy levels follow light. Photoreceptors in eyes absorb light, signaling the brain. This controls production of the sleep hormone melatonin. Light suppresses melatonin. So melatonin dips during daylight, making us energetic, but increases during dark, making us sleepy.
The researchers wondered how electric lighting affects us. After all, until recently, humans lived without it.
To find out, eight healthy volunteers wore wristband sensors. These measured light exposure as well as people's activity levels. Their melatonin levels were measured separately, via saliva samples.
For one week, the volunteers went about their normal lives. The next week? Camping! No electricity allowed! Only natural light!
Result? After camping just one week, all became morning people! Their melatonin cycle synched with natural daylight.
The researchers say getting sunshine each morning can produce similar happy effects.
Although s’mores can’t hurt either! Just sayin’.
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