Sleep Article

We are, as a population, sleeping less now than we ever have.

The problem, on the whole, isn’t that we’re waking up earlier. Much of the change has to do with when we choose to go to bed

When you go to bed affects how long you can sleep, no matter how tired you are.

Our clocks have evolved to anticipate tomorrow.

Part of how easily we go to sleep is genetic: many sleep disturbances, ranging from insomnia to circadian disruption, have a large genetic component. (Elizabeth Kolbert wrote about insomnia for this magazine, in 2013.) If you’re “out of phase” from typical bedtimes due to circadian disruption, for example, your melatonin levels are off: the hormone that should be telling you to fall asleep isn’t produced in enough quantity, or the requisite receptors are missing. While we are still a long way off from fully understanding the precise ways in which genes affect sleep in humans, the neurobiologist Dragana Rogulja, who studies the transition from wakefulness to sleep in Drosophila melanogaster, the fruit fly, has begun to answer that question for other animals. Many sleep genes, she points out, are conserved across species. And the sleep patterns in the flies, she told me, are remarkably similar to those in humans. One specific mutation in the flies’ genes can lead to a “sleep initiation deficit.” Isolating that gene and tracking its mechanism of action through the flies’ bodies and brains may bring us a step closer to understanding how similar deficits operate in human sleepers.

Even so, however, our genes haven’t really changed in the past century. Genetic predisposition can’t explain why so many of us have started to have more trouble falling asleep. The vast majority of the story has to do with our environment. Good “sleep hygiene,” many researchers have found, is essential when it comes to falling asleep; it can even overcome some unfortunate genetic predispositions. Conversely, bad sleep hygiene can equal, in its effects, some of the most problematic genetic disorders.

Some of the elements of sleep hygiene are basically the same as good health practices. Nicotine, caffeine, and alcohol all negatively impact sleep, the more so the closer they’re consumed to bedtime. We fall asleep faster when we exercise and have regular mealtimes. Eat too late or too much and sleep becomes more elusive. (The effect is reciprocal: sleep disturbance is associated with weight gain.) Go to bed hungry, and sleep likewise escapes your grasp.

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