Caffeine, large meals, and bright light in the evening induce circadian misalignment. That’s why these are better suited earlier in the day.
Caffeine reduces sleep pressure (which is supposed to start low in the morning and peak shortly after sunset) and delays melatonin onset (Burke et al., 2015). After dinner, make it a decaf or just pass.
Caffeine is an adenosine antagonist, and the accumulation of adenosine in the brain throughout the day is thought to be a chemical mediator of sleep pressure. Caffeine also delays and reduces melatonin, which increases your sleep needs, or at least time in bed/darkness.
It’s a circadian phase delay, and in today’s modern #context, most of us should be stacking the deck in the opposite direction. Fight against the niceties of technology and convenience. Assist sunset with blue blockers. Help co-entrain peripheral circadian rhythms with the master clock & light in the morning with breakfast. Get all these things right and you may even stop craving coffee in the morning *GASP*
KNOW THY ENEMY
Coffee is cool and all, and has been associated with a ton of health benefits, but in the grand scheme of things I’d say the most valuable benefit of coffee would be in helping to set the clock to a new time zone, like in jet lag (social or otherwise). In this #context, caffeine may be thought of as assisting sunlight in dopamine signaling (eg, Zheng et al., 2014 and Volkow et al., 2015)… but after a few days with your other circadian behaviors in order, I think you’ll find you need it less and less (it’s said to take one day to adapt for every hour of time zone shift, but I think we can do better).
By no means am I discouraging coffee. I love the stuff, and as mentioned above, it's associated with loads of health benefits.
However, caffeine alone is not sufficient to entrain circadian clocks. Skipping breakfast and only having a coffee in the morning won't cut it. That was at least partially demonstrated by showing 150 mg of caffeine in the morning wasn’t able to correct circadian arrhythmia in totally blind people (St Hilaire and Lockley, 2015). Caffeine may start the liver clock, but there are way more clocks out there which are governed by the food-entrainable oscillator. Gotta eat.
Humans are a pretty tough species; we can survive some fairly crappy conditions. But why am I even writing about this stuff?
Because the goal should be “optimal.”
Thriving >>> not dying … (the former relies heavily on circadian biology) (there's a big difference in quality of life between thriving and not dying)
If your goal is body recomposition, darkness & blue blockers at night and skewing your eating window earlier will help, regardless if you are a calorie-counter or not (eg, see studies by Jacobs & Hirsh, The Hunger-Free Diet(s), and the effects of artificial light at night on fat mass).
Reducing sedentary time and maybe even some actual heavy lifting will also help. If you opt for the latter, do it early in the day because exercise in the evening increases body temperature and stimulates the sympathetic nervous system at bedtime (Yamanaka et al., 2015). Neither bode well for sleep. Plus, if you're doing it in a gym, all that bright light and loud music ain't helpin'.
Morning exercise can also help re-adjust your sleep-wake cycle to a new time zone (Yamanaka et al., 2010). Plus, coffee can be an exercise-motivator, and coffee should be restricted to morning for the reasons mentioned above. And I still believe exercise should be performed around a big meal, which should also be morning.
see how all these things work together? IT'S NOT A COINCIDENCE
If your goals are circadian re-alignment or mood &/or behavioral, may need to add to the above some effort to get more outside sun time or at least more bright light in the morning.
(all of this is assuming you’re not eating like a child and playing on your smart phone in bed)
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