Feeling tired is just one tiny part of it.

You probably know that you should snooze for seven to nine hours each night, according to the National Sleep Foundation. But did you know that not sleeping enough may mean a higher risk of obesity, heart disease, and diabetes. Plus, naps can improve memory and even help make up for missing nightly Zzs. And it turns out that “beauty sleep” isn’t a myth. During sleep, your body releases a growth hormone that helps restore collagen and elastin, the essential building blocks of young, healthy skin, says Benabio.  Recent studies have also shown a connection between insomnia and accelerated aging of the brain, Benabio says. In other words, chronic lack of sleep adversely affects your brain’s function and speeds up the aging process. “Too many of us treat sleep as a luxury instead of a need,” says Benabio. “If I could encourage people do make one healthy change this year, it would be to sleep more.”
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The National Sleep Foundation recommends that adults get at least seven hours of sleep per night, and according to the 2014 Sleep Health Index, people are, on average, clocking in just enough, at seven hours and 36 minutes per night. Still, the CDC deems insufficient sleep a "public health epidemic," and despite the positive effects of rest, 42 percent of Americans still report fewer than seven hours of sleep per night. Not convinced that you need a full seven hours? Here's the latest consequence: Losing sleep may worsen memory and make recall more stressful.

The findings will be published in the journal SLEEP, and suggest that sleep is essential in ensuring proper function of memory recall, especially in times of stress. Researchers from Uppsala University in Sweden compared subjects who got eight hours of sleep to those who only had four, and found that the latter were not able to recall previously learned card pair locations without feeling stressed. Plus, the shortened sleep cycle reduced their recall abilities by 10 percent due to acute levels of stress experienced right after waking up. Those who slept a full night weren't stressed when asked to recall the card pairs.
 

"Interventions such as delaying school start times and greater use of flexible work schedules, that increase available snooze time for those who are on habitual short sleep, may improve their academic and occupational performance by ensuring optimal access to memories under stressful conditions," lead researcher Jonathan Cedernaes said in a statement.

This isn't the first time sleep has been linked to memory performance. Earlier research from Brandeis University showed something similar—all-nighters don't seem to be effective, because the brain needs sleep in order to convert short-term memories into long-term. And because sleep affects your ability to focus and concentrate, skimping on it impairs learning (and if you didn't learn something correctly in the first place, it's certainly hard to remember it). In the long-term, sleep loss has been linked to buildup of Alzheimer's disease, and may contribute to memory loss.

Treat yourself to an early bedtime—you won't regret it.