Night shift observation, offered as observation and nothing more: the two cheapest things that seem to help patients sleep on our unit are dimming the lights at 9pm and magnesium with the evening meds. One of those is free.

Labelling this personal experience, not evidence — though the magnesium literature isn't empty.

Melatonin as a sleep hormone is the least interesting thing about melatonin. The mitochondrial pool is produced locally, at concentrations well above serum, and behaves like an antioxidant system rather than a circadian signal.

Methodological caution: a lot of this work is in vitro at concentrations no oral dose reaches. I'm flagging my own citation as preclinical for exactly that reason. #epistemics