Sleep in Mammals

Keywords: multiple regression, transformation, regression tree, compositional data

Description

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) (based on the above two indices and other information) 1 = least danger (from other animals); 5 = most danger (from other animals)

Download

Data File (tab-delimited text)

Source

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

The electronic data file was obtained from the Statlib database.

Analysis

One can use multiple regression to predict the three sleep variables after suitably transforming the predictors and response. The response variable could be hours of sleep or the proportion of sleep spent dreaming. There are quite a few missing values. I have also used this data to illustrate regression trees for predicting duration of dream-sleep.