Recurring circadian disruption alters circadian clock sensitivity to resetting

Exposure to a 20-hour light cycle for over a month significantly alters circadian rhythms in male mice.

• A single phase advance in the light:dark cycle can disrupt neural circadian rhythms within the suprachiasmatic nucleus (SCN).
• Chronic exposure to disruptive light conditions affects the synchronization between SCN and peripheral tissues.
• Dissection timing strongly influences the circadian phase of PER2::LUC bioluminescent rhythms, varying by tissue type.
• White adipose tissue exhibits significant resetting by dissection, while thymus phase shows independence from dissection timing.
• Prior light exposure leads to strong resetting of SCN phase in mice subjected to a 20-hour light cycle.

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