Circadian quote of the day

Just got done reading this review by Yanielli Harrington (Prog. Neurobiol., 74: 59-76, which makes the following poignant observation in the discussion:

"Every 'photic' stimulus may involve photic–non-photic interactions, in that light may be arousing to a diurnal animal and anxiety-provoking to a nocturnal animal."

And though there's clear evidence of light inputs mediated only by the glutamate / PACAP RHT-to-SCN inputs, it is very important to remember that the major stimulus we use to measure phase-resetting of the circadian clock is likely to be aversive to the subjects we study (nocturnal rodents). The concept that the phase-shifting effects of the dark pulse in constant light during the subjective day is mediated in part by its arousal effects on the organism is fairly well established. The concept that the phase-shifting effects of the light pulse in constant darkness during the subjective night may also be modulated partly by its aversive effects is all too often not verbalized enough.