The Fact That Most People Sleep Almost Exactly the Same

Multiple Choice

The fact that most people sleep almost exactly the same amount each day under free-running conditions, despite large day-to-day variations in physical and mental activity provides strong support for the dominance of

A) recuperative factors in the regulation of sleep.
B) circadian factors in the regulation of sleep.
C) homeostatic light cycles in the regulation of sleep.
D) diurnal light cycles in the regulation of sleep.
E) diurnal temperature factors in the regulation of sleep.