'Normally, the periods of this type of sleep are short early in the night, then lengthen'
REM sleep
GENERAL SCIENCE: Normally, the periods of this type of sleep are short early in the night, then lengthen
Normally, the periods of this type of sleep are short early in the night, then lengthen
Normally, the periods of this type of sleep are short early in the night, then lengthen
GENERAL SCIENCE
REM sleep
GENERAL SCIENCE