What's Worse: Sleep Deprivation or Disrupted Sleep?

Skimping on your seven to eight hours of shut-eye might make you cranky, but it turns out even heading to bed on time can mess with your a.m. mood. It's tied to how you sleep-waking up throughout the night can affect your mood more negatively the following day than delaying your bedtime, says a new study from Johns Hopkins University.

In a three-day experiment, participants were woken up eight times throughout the night while others simply stayed up later than normal, typically getting less than five hours of zzz's total. After just two days, everyone was pretty grumpy. However, the forced-awake group reported a lot more negative emotions and significantly fewer positive ones. (Check out these 11 GIFs to Help People Who Can't Sleep.)

So how can eight hours of interrupted sleep be worse than a few hours sleeping straight through? "People who were forced awake lost more slow wave sleep," explains study author Patrick Finan, Ph.D., assistant professor of psychiatry and behavioral sciences.

While researchers aren't entirely sure the connection between mood and slow wave sleep-otherwise knows as deep sleep, or the third stage of non-REM sleep-Finan says some research suggests that the experience is crucial to forming positive emotional memories and overriding negative emotional memories. Without it, nothing is there to clean up your grumpiness and replace it with happier thoughts.

Finan's findings may explain why people with insomnia-which affects about 10 percent of the population-are so often depressed. Even for the rest of us, though, it sheds light on proper bedtime behavior before a big day.

How can you minimize the amount of times you wake up (and better your a.m. mood)? Finan recommends strategies referred to as "sleep hygiene," which include skipping your evening coffee, turning off the TV before you go to sleep, putting away light-emitting screens at a decent hour, and avoiding alcohol close to bedtime. (Can't disconnect? Learn 3 Ways to Use Tech at Night-and Still Sleep Soundly.)

P.S. Stress may be a contributing factor to disrupted sleep, Finan says. That means if you have, say, a big presentation or big race the next day, you're not going to be in a better place just by hopping into bed at a decent hour. (Try these 3 Breathing Techniques for Dealing with Anxiety, Stress, and Low Energy.) Tackle your stress before you slide in between the sheets, and you'll be more likely to wake up on the right side of the bed.