sound asleep

asleep at the switch

Neglectful of an important task, responsibility, or opportunity.

dead asleep

Sleeping in a deep sleep

fall asleep

To be affected by paresthesia; to go numb.

fast asleep

Sleeping, in a deep sleep.

I can't hear you over the sound of

Said to dismiss what the interlocutor is saying.

like the sound of one's own voice

To talk a lot.

safe and sound

Having come to no harm, especially after being exposed to danger.