Light at Night for Mice


Data from an experiment with mice having different nighttime light conditions


A dataset with 27 observations on the following 9 variables.

  • Light DM=dim light at night, LD=dark at night, or LL=bright light at night

  • BMGain Body mass gain (in grams over a four week period)

  • Corticosterone Blood corticosterene level (a measure of stress)

  • DayPct Percent of calories eaten during the day

  • Consumption Daily food consumption (grams)

  • GlucoseInt Glucose intolerant? No or Yes

  • GTT15 Glucose level in the blood 15 minutes after a glucose injection

  • GTT120 Glucose level in the blood 120 minutes after a glucose injection

  • Activity A measure of physical activity level


In this study, 27 mice were randomly split into three groups. One group was on a normal light/dark cycle (LD), one group had bright light on all the time (LL), and one group had light during the day and dim light at night (DM). The dim light was equivalent to having a television set on in a room. The mice in darkness ate most of their food during their active (nighttime) period, matching the behavior of mice in the wild. The mice in both dim light and bright light, however, consumed more than half of their food during the well-lit rest period, when most mice are sleeping.


Fonken, L., et. al., "Light at night increases body mass by shifting time of food intake," Proceedings of the National Academy of Sciences, October 26, 2010; 107(43): 18664-18669.

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