If you didn’t sleep all that great last night, having a cup of coffee in the morning will help bring you back to something close to normal. This is something we all know to be true. We don’t need scientists to prove this to us, but they did anyway. Newly published in Progress in Neuro-Psychopharmacology and Biological Psychiatry, German scientists have discovered that, yep, coffee can make up for sleep loss.

Of course, the scientists made it sound a bit more technical than that, stating that “caffeinated coffee can temporarily mitigate repercussions of reduced sleep,” per News-Medical.net. Specifically, they found that caffeinated coffee can provide performance boosts in attention and cognitive function for those who undergo repeated days of not getting enough sleep, like, y’know, a regular work week.

For the study, 26 participants underwent a nine-day controlled sleep study at the Institute for Aerospace Medicine in Cologne, Germany. A week prior to the study, all participants were required (and monitored) to regularly get nine hours of sleep a night and refrain from naps, caffeine, or alcohol. During the 9 days, participants were restricted to five hours of sleep, with one group being given caffeinated coffee and another getting decaf. The two groups were underwent tests to assess their alertness and attention to detail. Researchers found that the decaf group began experiencing performance impairment in these tests after one day of sleep restriction for speed-based tests and three days for accuracy-based tests. The impairment continued until the group received a recovery night of full rest.

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By contrast, the caffeinated group actually outperformed their baselines on days one and two before experiencing impairment on days four and five. Like the decaf group, the impairment stayed until after a recovery night.

These findings suggest, per the researchers, that caffeinated coffee can have short-term positive effects on those experiencing repeated sleep loss, but those benefits go away after the fourth or fifth day of consecutive restricted sleep. So if you seem unshakably tired on Fridays, now you know why.

And while caffeinated coffee is an effective temporary band-aid for a bad night’s rest, researchers note that it is no substitute for a quality eight to nine hours of sleep. What they don’t note, though, is that coffee tastes better than sleep does. Seems like a pretty big oversight IMO. But to be on the safe side, get a good night’s sleep and then have coffee. Win win.

Zac Cadwalader is the managing editor at Sprudge Media Network and a staff writer based in Dallas. Read more Zac Cadwalader on Sprudge.

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