He wakes during the night or early morning and finds it difficult to fall asleep again.
他晚间或清早醒来后，再也不能入睡。

He has difficulty in sleeping, inability to concentrate.
他不易入睡，也难集中精神。

He has nightmares occasionally.
他有时做噩梦。

It is usually hard for her to fall asleep when she goes to bed at night.
她晚上就寝，很难入睡。

He is sleeping poorly.
他睡不好。