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Do you ever wake up feeling groggy, unsure if you've just had a horrible night's sleep or if, instead, you simply need a few more minutes to shake off the past several hours of unconsciousness?
There are a few ways to tell, according to sleep scientist Patrick Fuller, associate professor of neurology at Harvard Medical School.
Luckily, none of them involve hooking a bunch of wires and monitors to your head or tracking your sleep patterns for days.
If you woke up naturally without an alarm clock, as opposed to forcing yourself out of bed, Fuller said, then you've probably just had a good snooze.
While we still don't know for sure why we sleep, we do know what it's supposed to feel like when done correctly. According to Fuller, it should be restorative, leaving you feeling refreshed and able to tackle the day.
If you then find that after you've gotten out of bed and started working and your brain is functioning at its peak level without having to drink "10 cups of coffee to get to that level," Fuller said, particularly for the first half of the day, then you're also likely getting enough sleep.
Of course, your peak level will be different from your neighbor's peak level, so this is a very personal measure. If we were doing a controlled study in humans, Fuller said, we'd do a bunch of cognitive tests to see if each person is performing work tasks at a consistent level each day. If it begins to decrement in any way, he said, other issues aside, this would point to a sleep deficiency.
You're not going to do this kind of controlled study on yourself, obviously. The trick is to decide if your energy level today deviates from your typical day-to-day energy level. If it does, then there's possibly something going on with your sleep.
And don't worry if you start to get sleepy later in the day, that's normal.
"We do tend to get a little drowsy at some points during the day," Fuller said. "But if you're getting into work and you're doing it at the level that you've always done work at, then you're probably fine."
READ MORE: 7 things a sleep scientist does to get a good night's sleep
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