Why are we groggy/tired when we wake up?

We’re going to start off with something which we’ve all experienced, why, when we wake up, are we often as tired or more tired than when we went to sleep? Let’s firstly think why do we need sleep? Well that’s something science has yet to answer definitively and at the moment we do not have a clear answer as it has been linked to development in children, restoration of the body and healing, conserving energy in times where we would use much less (due to factors such as a lower metabolism), and even that it was an evolutionary defence to keep animals out of a nocturnal predator’s way, and as it is likely to be a mixture of these and not any one specific function we probably won’t know for certain any time soon.

What we do know a fair amount about, is what actually happens in our heads happens when we sleep; this can be split into 4 stages. Stage 1 is light sleep, this is when we first fall asleep and we begin to calm down. Stage 2 is true sleep, our breathing and heartrate are slow, we then enter stages 3 and 4 which are REM or rapid eye movement sleep, where all the fun stuff like dreams and nightmares happen, these last for about 30 minutes at a time, although this decreases with age, and the whole cycle can take up to 110 minutes repeating every 90 minutes.

If we are woken up during the REM section of this cycle then we tend to feel groggy as our minds attempt to adjust from sleeping to being awake, effectively this feeling of grogginess otherwise known as “sleep inertia”  is caused as the brain is powering up, ready for the day. So if you want to beat that Monday morning feeling try getting up twenty minutes earlier, but that’s probably not going to happen. Anyhow now that the question has been answered goodbye until next week. Thanks for reading :)