Sleep in Mammals

Includes brain and body weight, life span, gestation time, time sleeping, and predation and danger indices for 62 species of mammals. Of interest is to predict the time spent sleeping and the proportion of sleep time in dream sleep.
	
Variable 		Description
	
BodyWt 		body weight (kg)
BrainWt 		brain weight (g)
NonDreaming 		slow wave ("nondreaming") sleep (hrs/day)
Dreaming 		paradoxical ("dreaming") sleep (hrs/day)
TotalSleep 		total sleep, sum of slow wave and paradoxical sleep (hrs/day)
LifeSpan 		maximum life span (years)
Gestation 		gestation time (days)
Predation 		predation index (1-5)
			1 = minimum (least likely to be preyed upon); 
			5 = maximum (most likely to be preyed upon)
Exposure 		sleep exposure index (1-5)
			1 = least exposed (e.g. animal sleeps in a well-protected den); 
			5 = most exposed
Danger	 		overall danger index (1-5) 
			1 = least danger (from other animals); 
			5 = most danger (from other animals)
	

Allison, T., and Cicchetti, D. V. (1976). Sleep in mammals: ecological and constitutional correlates. Science 194 (November 12), 732-734.

EXERCISE: 
Study the 2 possible response variables:
- hours of sleep
- proportion of sleep spent dreaming