The eight-hour misconception is one that Rafael Pelayo, M.D., a professor at Stanford Medicine and the author of How To Sleep: The New Science-Based Solutions for Sleeping Through the Night, comes up against time and time again in his line of work. Another board-certified sleep specialist Michael J. Breus, Ph.D., also named it as one of the most common myths in the sleep space on a recent episode of the mindbodygreen podcast. There are, of course, also outside factors that could shift how much rest you’ll need to wake up feeling alert. Here are a few that Breus and Pelayo note: This idea that our sleep needs shift over the course of a year makes sense from an evolutionary perspective, too. “How could we really be eight-hour sleepers if mothers have to feed their babies every two to three hours when they’re nursing?” he says. “There has to be this mechanism built into our brains to avoid sleeping under certain circumstances. You have to be able to push off sleep, take care of something, and go back to sleep later. There’s got to be some flexibility in the system.” Most people will feel their best when they wake up after completing a full sleep cycle, which lasts around 90 minutes. By this logic, timing your sleep in 90-minute increments isn’t a bad idea. Once you find your ideal number—or ideal range—stick to it! When it comes to sleep, the experts stress that consistency is key. That means going to bed and waking up at around the same time every day, even on weekends. Pelayo adds that it’s important to leave yourself some wiggle room, too. So if you know you need 7.5 hours of sleep to function at your best, don’t get into bed exactly 7.5 hours before your alarm is set to go off. “As you get older and life gets more complicated, you learn the amount of sleep you need, and that’s what you home in on,” he says, adding that constantly teetering on a razor’s edge like this can make you more vulnerable to the unfortunate side effects of a night of poor sleep. “If you always sleep as little as possible and then don’t sleep, the next day you’re a basket case.” Emma received her B.A. in Environmental Science & Policy with a specialty in environmental communications from Duke University. In addition to penning over 1,000 mbg articles on topics from the water crisis in California to the rise of urban beekeeping, her work has appeared on Grist, Bloomberg News, Bustle, and Forbes. She’s spoken about the intersection of self-care and sustainability on podcasts and live events alongside environmental thought leaders like Marci Zaroff, Gay Browne, and Summer Rayne Oakes.
