Question: Why are we sleepy when we wake up in the morning?

Michael Cook answered on 29 Jun 2012:

Here’s one reason for this (it’s not the only one, there are lots of reasons for why you might be tired in the mornings!):

When we sleep, we go through cycles of activity. Sometimes we’re sleeping very lightly, when it’s easy to wake up. Other times, our body goes into a much deeper sleep – it’s harder for us to sense the outside world, and much harder to wake up. Deep sleep is when people sleepwalk and talk in their sleep: that’s how hard it is for them to wake up!

The thing is, we live in a world where there are dates, times and deadlines! If you have to be in at 9am, you might set an alarm for 7.30am. If you’re sleeping deeply at 7.30am, that alarm is going to yank you out of deep sleep, whether you like it or not. It’s much harder to wake up and feel alert and active if you wake up during a period of deep sleep. Unfortunately it’s hard to predict when you will be in deep or light sleep, and also hard to guess when exactly you will start sleeping.

Like I say, though, there are other reasons too – you might be so tired you didn’t get enough sleep, for instance. Being dehydrated can also make it harder to wake up and feel normal in the morning.