Where does “photoperiod” come from?

I need to point out an issue: the chain provided is for "period," not "photoperiod." Photoperiod is a compound word (photo- + period), so I cannot write an accurate etymology for it using only this chain, as it doesn't account for the "photo-" element. If you'd like me to write the origin summary for **period** using this chain, here it is: Period comes from Middle English periode, from Middle French periode, from Latin periodus, from Ancient Greek περίοδος meaning a journey around or circuit, derived from Proto-Indo-European bʰeh₂- and sed-. However, this contains a logical problem: the chain shows bʰeh₂- twice and ends with sed-, but doesn't explain how these roots combine or which contributes which part of the meaning. Could you clarify the chain, or did you mean to ask about "period" rather than "photo

photoperiod (English): The normal duration of natural daylight...