易醒的人，睡觉轻的人
someone who is easily woken up by noise, etc.
I'm a very light sleeper.
He was a light sleeper and woke every time a train went by.
She was a light sleeper who found it difficult to get back to sleep.
Her baby was such a light sleeper, he woke up whenever she entered the room.
I am a light sleeper but I didn't hear anything.
See also: light adjective (NOT MUCH)