R Dataset / Package lme4 / sleepstudy


On this R-data statistics page, you will find information about the sleepstudy data set which pertains to Reaction times in a sleep deprivation study. The sleepstudy data set is found in the lme4 R package. You can load the sleepstudy data set in R by issuing the following command at the console data("sleepstudy"). This will load the data into a variable called sleepstudy. If R says the sleepstudy data set is not found, you can try installing the package by issuing this command install.packages("lme4") and then attempt to reload the data. If you need to download R, you can go to the R project website. You can download a CSV (comma separated values) version of the sleepstudy R data set. The size of this file is about 3,061 bytes.

Reaction times in a sleep deprivation study


The average reaction time per day for subjects in a sleep deprivation study. On day 0 the subjects had their normal amount of sleep. Starting that night they were restricted to 3 hours of sleep per night. The observations represent the average reaction time on a series of tests given each day to each subject.


A data frame with 180 observations on the following 3 variables.


Average reaction time (ms)


Number of days of sleep deprivation


Subject number on which the observation was made.


These data are from the study described in Belenky et al. (2003), for the sleep-deprived group and for the first 10 days of the study, up to the recovery period.


Gregory Belenky, Nancy J. Wesensten, David R. Thorne, Maria L. Thomas, Helen C. Sing, Daniel P. Redmond, Michael B. Russo and Thomas J. Balkin (2003) Patterns of performance degradation and restoration during sleep restriction and subsequent recovery: a sleep dose-response study. Journal of Sleep Research 12, 1–12.


xyplot(Reaction ~ Days | Subject, sleepstudy, type = c("g","p","r"),
       index = function(x,y) coef(lm(y ~ x))[1],
       xlab = "Days of sleep deprivation",
       ylab = "Average reaction time (ms)", aspect = "xy")
(fm1 <- lmer(Reaction ~ Days + (Days|Subject), sleepstudy))
(fm2 <- lmer(Reaction ~ Days + (1|Subject) + (0+Days|Subject), sleepstudy))

Dataset imported from https://www.r-project.org.

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Attachment Size
dataset-85663.csv 2.99 KB
Dataset License
GNU General Public License v2.0
Documentation License
GNU General Public License v2.0

This documentation is licensed under GPLv3 or later.