Researchers say that normal people may have four or five REM periods of dreaming a night.
Four or five REM periods of dreaming take place during a ................ sleep.
good night's sleep
In my personal opinion, I will go for No.2#. I think the word "normal" is only for "people" in the given sentence . The word "good night's sleep" is more natural, but the word "good" is not used in the given sentence.So I prefer No.2# to others.
Please share your possible answers with me. Thanks in advance.