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This is Scientific American's 60-Second Science. I'm Karen Hopkin. This will just take a minute.

For those of you who’ve spent many of your waking hours this winter washing your hands and fretting¹ about getting sick, you might be better off just staying in bed. Because scientists from Stanford University have found that the immune system works best after dark.

The scientists were studying fruit flies, which are active at dawn and dusk, and sleep through the night like you and me. The circadian rhythm that tells these critters, and many others, when to snooze and when to cruise, controls lots of bodily functions. So the scientists got to wondering whether it also regulates the immune system and the fly’s ability to fight infections. Yes, even fruit flies can catch some pretty nasty bugs². Which the scientists proceeded to demonstrate.

They took a bunch of flies and infected them with some unsavory bacteria. Half the flies were infected while they slept, half while they were awake. Turns out that the flies that were infected at night were better able to battle their bugs than flies who got sick during the day, results presented at the American Society for Cell Biology meeting in San Francisco on December 14th. Whether human immunity³ is also better during sleep isn’t yet known. But Shakespeare might have been onto something when he called sleep “nature’s soft nurse.”

Thanks for the minute for Scientific American's 60-Second Science. I'm Karen Hopkin.