Teens stay up late because they want too and because their natural body clock and circadiam rhythms change.
So that is another reason the teens stay up late because the teens sleep habits change and they are changing through hormones such as the sleep hormones changing in their bodies.
However teens need to try to sleep as much as possible so that the teen gets enough sleep at night for the best health and to function the next day.
But if the teen is getting enough sleep then it's okay for the teen to stay up late.
Sleep does affect your height and growth.
When you sleep your body releases a growth hormone that helps your body grow and when you do not get enough sleep then your body will not be able to release enough of that growth hormone.
Then when your body does not get enough of that growth hormone your height and growth suffer.
As you sleep your body is repairing itself and recharging itself and you're growing a little at a time at night while you sleep.
So you need to make sure you get enough sleep so you grow properly and have optimal health.
Sleep is a very necessary thing for our health and well being and to keep us alert the next day and sleep also helps us to function properly.
Lack of sleep can lead to heart disease, heart attacks, strokes etc.
Lack of sleep also causes accidents and especially when driving as you're not very alert when you lack sleep.
So aim to get at least 8 hours of sleep at night and more if possible.
I get at least 8 hours of sleep on the weekdays and on the weekends when I can sleep in longer I try to get 10 to 11 hours of sleep.
I feel much better when I get at least 8 hours of sleep but I feel even better when I get 10 hours of sleep.