PT  - JOURNAL ARTICLE
AU  - Jeffrey Hubbard
AU  - Mio Kobayashi Frisk
AU  - Elisabeth Ruppert
AU  - Jessica W. Tsai
AU  - Fanny Fuchs
AU  - Ludivine Robin-Choteau
AU  - Jana Husse
AU  - Laurent Calvel
AU  - Gregor Eichele
AU  - Paul Franken
AU  - Patrice Bourgin
TI  - Melanopsin-dependent direct photic effects are equal to clock-driven effects in shaping the nychthemeral sleep-wake cycle
AID  - 10.1101/2020.02.21.952077
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.02.21.952077
4099  - http://biorxiv.org/content/early/2020/02/26/2020.02.21.952077.short
4100  - http://biorxiv.org/content/early/2020/02/26/2020.02.21.952077.full
AB  - Nychthemeral sleep-wake cycles (SWc) are known to be generated by the circadian clock in suprachiasmatic nuclei (SCN), entrained to the light-dark cycle. Light also exerts direct acute effects on sleep and waking. However, under longer photic exposure such as the 24-hour day, the precise significance of sustained direct light effects (SDLE) and circuitry involved have been neither clarified nor quantified, as disentangling them from circadian influence is difficult. Recording sleep in mice lacking a circadian pacemaker and/or melanopsin-based phototransduction, we uncovered, contrary to prevailing assumptions, that circadian-driven input shapes only half of SWc, with SDLE being equally important. SDLE were primarily mediated (>80%) through melanopsin, of which half were relayed through SCN, independent of clock function. These findings were used for a model that predicted SWc under simulated jet-lag, and revealed SDLE as a crucial mechanism influencing behavior, and should be considered for circadian/sleep disorder management and societal lighting optimization.