Sleep is a much-coveted enterprise. And as researchers learn more and more about its purpose – and the fallout of not getting enough – the importance of getting a good night’s sleep becomes even clearer. A new study by Johns Hopkins researchers shows that there’s a difference between sleep that’s long but interrupted and sleep that’s short but sound. As you might guess, it’s better for the brain to sleep for a shorter number of uninterrupted hours than a longer number of fitful ones.
“When your sleep is disrupted throughout the night,” says study lead author Patrick Finan, “you don’t have the opportunity to progress through the sleep stages to get the amount of slow-wave sleep that is key to the feeling of restoration.”
He and his team had people come into the sleep lab and get a full night’s sleep, stay up late so their total sleep would be reduced, or be subject to multiple interruptions throughout the night. It turned out that after the second night a pattern emerged: the people who’d had interrupted sleep reported significantly reduced positive moods the next day than people in the short-but-uninterrupted group. They had lower energy levels, and reduced ratings of positive feelings like sympathy and friendliness.
Not only do the results apply to “healthy” people, but they’re very likely to apply to those who sleep poorly as a matter of course. One in ten people has insomnia, and if you’re one of them, you probably don’t need scientific studies to know how much it takes its toll, especially over time. Previous studies have shown that both too few and too many hours of sleep are linked to a number of health problems over time, and even to early mortality. There seems to be a sweet spot for sleep — about seven hours, give or take, depending on the individual — and too far outside of this window, in either direction, can indicate underlying problems.
Below are the sleep habits of 21 highly successful people throughout history (the original graphic can be viewed here). Not everyone keeps “normal” hours, as is shown, but it’s important to do what feels right for you, tweaking your pattern as needed. Since sleep is right up there with nutrition and exercise in terms of its role in health, make sure to give it the attention it deserves. If you can’t get as many hours as you need at night, it’s totally legit to take a nap, and many experts even recommend it. Here are some more healthy sleep tips from the National Sleep Foundation.