dreamfully
His eyes closed, and for the first time in ages he slept dreamlessly.
She slept so deeply and dreamlessly that when she woke up she wasn't sure where she was.
He slept dreamlessly, and awoke to the sound of people moving about downstairs.
He slept heavily and dreamlessly.

SMART Vocabulary: related words and phrases

Animal physiology: sleep & sleeping
altered state of consciousness
beauty
bed
bunk
bye-byes
catch/cop/get some z'sidiom
comatose
count
crash
doss
drift off
power nap
sleep
sleepwalk
sleepwalking
snooze
snoozing
somnambulate
somnambulist
your beauty sleepidiom

You can also find related words, phrases, and synonyms in the topics:

Dreaming