What causes grogginess when you first wake up – what about your brain isn’t working?

Question

What causes grogginess when you first wake up – what about your brain isn’t working?

In: 956

Answer 1

I heard that if you set your alarm twice – the first one being 90 minutes prior to the time you want to get up – you won’t feel groggy. It’s because a cycle lasts 90 minutes on average and getting up in the middle of it causes the heavy, groggy feeling.