Curious Odor Released from Plants right when Lights Go Off

I've been noticing this for awhile, that right when the lights shut off in the grow closet at night, immediately there is a unique smell present, like the plants release an odor right when they shift into their dark sleep time. It smells "green", and not like green as in buds, but green as in a very green, living plant. It overpowers the bud scent and is very obvious. It lasts for about a minute or two, then it's gone completely. I do not ever smell it right when the plants wake up and the lights come on, it is only when the lights go off.

Why do the plants release this odor?

my junior said the same the other day

my reply is

" breathe it in deep baby thats pure 02'..lol

indeed the stomatas may close releasing any built up gas

see it as the gas of photosynthesize or chlorophyll

good luck