Photoperiod: the length of time spent exposed to light, whether sun or artificial light.

ipRGCs, “intrinsically photosensitive retinal ganglion cells” (“dots”): the third kind of photosensor present in the human eye; quite distinct from rods or cones. Insensitive to red light, these sense night and day and control the majority of the human hormone system.

Overview of the Photoperiod Effect

Pathways to Chronic Illness

Metabolism, Melatonin, and more

  Remember the five rules for healthy nights:

1) Very consistent beginning and end times of
2) uninterrupted 3) true darkness for at least
4) nine or ten hours, while 5) never sleeping in
during morning light.

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Contact: at photoperiodeffect.com