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Respiratory frequency and tidal volume exhibit daily, 24-hr rhythms in human and rodent models. Environmental light has emerged as a potential modulator of ventilatory rhythmicity, as mice lacking intrinsically photosensitive retinal ganglion cells fail to alter their breathing in response to light. Despite this evidence, it remains unknown how the duration of light exposure influences breathing in mice. To assess the effects of light exposure on breathing, male wild-type mice (n = 8) were exposed to broad-spectrum white light (~450 lux) in the standard dark phase, either for 3h (ZT 13-16) or for 5 minutes (ZT13-13.05). Respiratory measures were assessed for 36 hours using whole-body plethysmography. To determine whether the light manipulation produced significant deviations from expected respiratory patterns, a nonparametric, within-subjects bootstrapping approach was conducted in R. This compared parallel time points between a predefined test period and the equivalent control period without a light manipulation. We found that a 3h light stimulus administered during the standard dark phase reduced tidal volume and respiratory frequency for ~80 minutes during light exposure. Immediately following the offset of the 3h stimulus, respiratory frequency was increased for 2h compared to control. While statistical analysis is currently ongoing, a 5-minute light stimulus appeared to decrease both tidal volume and respiratory frequency during light exposure. In contrast to a 3hr stimulus, both tidal volume and respiratory frequency were increased at 90 minutes following the offset of the 5-minute light stimulus. While preliminary, these data suggest that tidal volume and respiratory frequency differentially respond to the duration of environmental light exposure. Subsequent research is required to determine if tidal volume is specifically responsive to shorter light durations and the extent to which a 3h light stimulus may be “masking” the tidal volume response. This work expands upon our current understanding of respiratory physiology to include light duration as a key variable affecting daily breathing