You wake up, for no apparent reason, at 5:03 a.m.—and your alarm is set for 6.

Do you take advantage of an early start on the day or try to catch some more sleep?

The best answer depends on a few factors, experts tell Fortune, but generally leans toward heading back to bed. That’s because sleep has restorative properties and impacts multiple body systems.

The first question to ask yourself: whether or not you’ve gotten the recommended seven to nine hours of shut-eye. That’s according to Joachim Behar, a sleep researcher and the head of the Artificial Intelligence in Medicine Laboratory at the Technion – Israel Institute of Technology in Haifa, Israel.

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