To sleep for a brief moment in order to recharge energy.
Take a power nap.
The kids played amazingly ___ they couldn't sleep all night.
Considering that
___ nobody disturbs my sleep, I wake up in a good mood.
As long as
To gradually start to fall asleep to the point you fall deeply asleep.
Drift off.
A deep sleep, so strong that nothing can wake you up.
Sleep like a log.
I tell my mother to wake me up ___ I don't hear my alarm.
(Just) in case.
To begin sleeping, especially not intentionally.
Nod off.
To sleep well and deeply.
Be fast asleep / Be sound asleep
To be awake and completely active.
Be wide awake.
When some nights you have problems falling asleep.
Have a sleepless night.
Being in a state between sleeping and being awake.
Feel Drowsy.
To move around the bed unable to fall a comfortable position to fall asleep.
Toss and turn.