Adequate sleep has been linked to everything from better mood to a higher salary, but Americans are sleeping less than ever. The New Yorker's Maria Konnikova spoke with experts to find out why and learn how people can improve their sleep health.
Over the past fifty years, Americans' average amount of sleep on work nights has fallen from eight and a half hours to less than seven, says Charles Czeisler, the chief of the Division of Sleep and Circadian Disorders at Brigham and Women's Hospital (BWH). And nearly a third of people sleep fewer than six hours a night.
Worsening sleep habits have more to do with when people go to bed than when they wake up, Konnikova writes. "When you go to bed affects how long you can sleep, no matter how tired you are," says Elizabeth Klerman, head of BWH's sleep and circadian disorders Analytic and Modeling Unit.
At the root of the problem is how our environment impacts our circadian rhythms, Klerman explains. The body produces hormones that promote sleep—such as melatonin—in response to environmental stimuli. Light, in particular, plays an important role in promoting sleep. "In fact, there are specific photoreceptors in the eye that only respond to changes in light and dark, and which are used almost exclusively to regulate our circadian rhythms," Konnikova writes.
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Hunger, stimulants, and other substances can also affect sleep—but researchers say the light from smartphones, computers, and other devices is particularly harmful. These devices produce "blue light," which our body interprets as daylight. A recent study by Czeisler and his colleagues found people who read a light-emitting e-book for about four hours before bed for five straight days took longer to fall asleep and were less alert in the morning.
In the lab, it has taken less than 12 minutes of exposure to blue light for sleep to be disrupted, says Steven Lockley, a Harvard University circadian neuroscientist.
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Pharmaceutical sleep aids may not have much of an effect. Matt Bianchi, chief of the Sleep Medicine Division at Massachusetts General Hospital, says such drugs only increase sleep time by 30 to 40 minutes on average. Such medications also reduce REM and can "impair the restorative value of sleep," he says.
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Czeisler and Lockley are championing a low-tech solution to promote high-quality sleep. The pair has developed a set of lights that change throughout the day to promote wakefulness and sleepiness at the appropriate times. NASA plans to install the lights on the International Space Station in 2016.
Back on Earth, consumers can purchase blue-light filters for their electronic devices or engage in sleep-promoting activities. For instance, Susan Redline, a sleep researcher at Harvard, says yoga and mindfulness exercises can help people get the rest they need (Konnikova, The New Yorker, 7/7).
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