Splitting the internal body clock leads to flexible timing by lowering its strength

Behavioral jet lag after simulated time-zone travel is virtually eliminated following bifurcated circadian entrainment under a novel 24-h light:dark:light:dark (LDLD) cycle.

• The suprachiasmatic nucleus (SCN) and peripheral tissues exhibit changes in oscillatory stability when exposed to the LDLD cycle.
• Dissection as a resetting stimulus resulted in a stronger phase setting of cultured tissues under LDLD compared to a normal light:dark cycle.
• Acute bioluminescence analysis revealed reduced rhythm amplitude and altered phase of the PER2 gene in SCN explants under LDLD.
• Significant reductions in amplitude and rhythmicity of clock genes were observed in the lung, liver, and kidney when analyzed in vivo under LDLD.
• Spatiotemporal patterns of PER2 peak times in cultured SCN were altered in the LDLD condition.

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