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Sleep in Mammals

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


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)


Data File (tab-delimited text)


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.


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.



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