The impact of self-selected light on activity rhythms in the diurnal striped mouse

Apr 8, 2026Current biology : CB

How choosing their own light affects daily activity patterns in daytime-striped mice

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Abstract

Rhabdomys pumilio displays a circadian rhythm in light intensity preference, choosing darkness during inactivity and bright light during activity.

Self-selected light (SSL) can disrupt circadian rhythms and sleep patterns.
Under specific light conditions, SSL increases dark phase activity and may lead to disrupted synchronization with external light:dark cycles.
Bright light is preferred during active phases, indicating an innate response to light in R. pumilio.
SSL does not worsen existing phase angle issues caused by social jet lag but can significantly delay re-entrainment to changes in the light cycle.
The findings suggest that intrinsic relationships between light exposure, arousal, and circadian timing may contribute to the disruptive effects of SSL.

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Access to self-selected light (SSL) breaks the ancient relationship between light and time of day and can disrupt sleep and circadian rhythms in humans. Such disruptions have been explained in terms of established features of circadian photosensitivity and positive associations between arousal and light. We address the potential of such intrinsic relationships to recapitulate the disruptive effects of SSL in a day-active rodent (Rhabdomys pumilio [R. pumilio]) that lacks the additional human drivers to consume light for work, care, and leisure. R. pumilio learns to SSL spontaneously and expresses a circadian rhythm in light intensity preference (choosing darkness and brightest available light for inactive and active phases, respectively), which feeds back to modify circadian period (τ) and extend active phase (α). Under imposed light:dark (LD) cycles, SSL can lead to increased dark phase activity and disrupted entrainment when SSL irradiance is ≥ imposed light. SSL does not exacerbate aberrant phase angles of entrainment in simulated social jet lag but can substantially delay re-entrainment to shifts in the external LD cycle. Our findings establish bright light as an innate preference in R. pumilio and are consistent with intrinsic relationships between light, arousal, and the clock being an origin for the disruptive effects of SSL.

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Circadian BiologyIssue #32

Bright light preference disrupts mouse sleep patterns even without human lifestyle factors

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The impact of self-selected light on activity rhythms in the diurnal striped mouse

Abstract

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