What constitutes “staying up late”
So how do you know if you are staying up late? Is 10pm late? Is 1am late? Actually, it depends. You know you are staying up late by one single signal. You are tired. If you are up late enough to be tired you know that you are going past your body’s bedtime. And this bedtime is different for everybody. Some people need to be in bed by 8pm. Others can stay up all night studying and not feel tired at all.