Seasonal Rhythms
infradian rhythms (longer than one day)
Chronopharmacology
the timing of medicine matters. traditional medicine knew this!
The Liver
CYP1A2 is a liver enzyme that breaks down pharmaceuticals and drugs like coffee.
It's transcription is rhythmic! So taking medicine / drugs / coffee at certain times of the day can stay in the system for longer or shorter periods of time!
Sleeping In
What happens to early morning steroid-synthesis if one sleeps in? What is the optimal time to wake up for this to happen?
Corticotrophin starts to build 2 - 4 AM (vata time of day).
"If you consistently wake much later than sunrise, your circadian system can partially shift the steroid peak to match your schedule, but it usually doesn’t shift as much as your wake time — so the amplitude of the CAR may shrink." - is this true? what is it about sunrise that matters if corticotrophin is building at 2 - 4 AM? is it anticipating sunrise?
consistent wake times seems to be what matters for steroid synthesis
does it matter if you're asleep during steroid synthesis times?
what happens to human biorhythms in places like antartica, where it can be dark all day and night?
Cortisol Cycle
It seems to make sense to sync my cortisol levels with the cortisol cycle, doing the most stressful activity of the day at 8:30am
Sandhyavandanam
"In animal chronobiology, zeitgebers (time-givers like light) are most powerful during phase transition windows — which align closely with these periods."
Suprachiasmatic Nucleus
Right behind the optic chiasm (where the eye nerves)
how does light somehow go through the eyes, get "translated?" into the optic nerves, or received by the optic nerves through the rods and cones, and then how does this nerve information reach the suprachiasmatic nucleus, and in what format? like, computers send bits in 1s and 0s, how do nerves encode information? what's the protocol?
https://arc.net/l/quote/jwqbirlq - As noted previously, diurnal rhythmicity is observed in essentially all endocrine systems. For many of these systems, alterations in timing, changes in amplitude, and even the total absence of rhythmicity have been associated with a variety of endocrine, metabolic, and psychiatric disorders. For example, hypercortisolism and alterations in the low point in the cortisol rhythm have been associated with severe depression, while growth hormone levels are markedly suppressed in obese subjects.
Library
Circadian Physiology — Roberto Refinetti
Ultradian Rhythms from Molecules to Mind
Ultradian Rhythms in Life Processes — Lloyd & Rossi
The discoveries of molecular mechanisms for the circadian rhythm: The 2017 Nobel Prize in Physiology or Medicine - 2017
Molecular regulations of circadian rhythm and implications for physiology and diseases - 2022
Endocrine regulation of circadian rhythms - 2025
"Hands-on (1 week): grab an omics/time-course dataset (GEO) and run MetaCycle (follow CRAN vignette). Plot Cosinor fits for a few genes. This will teach you how rhythm detection papers are done."