Social jet lag

Social jet lag is basically a general term that refers to circadian arrhythmia.  Sort of like insulin resistance, it’s rampantly abundant — some have estimated a prevalence of up to 75%!  Social jet lag can be induced by shift work, East/West travel, late meal timing, artificial light at night, sleeping late, not enough sunlight in the morning, etc., etc.  And while any of the above insults, by themselves, may not really screw up your circadian rhythms, you can see how easy it is for one person to fall prey to nearly of them:

Eat a late dinner, stay up late using artificial light (eg, computer, smart phone, etc.), sleep late the following day so you skip breakfast and don’t get any sunlight in the morning.


This increases your risk for a wide variety of ailments, ranging from cancer to diabetes to bipolar disorder: no bueno.

One key mediator of the effects of LIGHT is melatonin.  Artificial light at night suppresses melatonin.  Sunlight in the morning can blunt the impact of this!  It all ties in together.  Gravitas.

Great review article here.



Jane Plain noted that cortisol is anti-proliferation and the AM cortisol spike (also known as the Cortisol Awakening Response) blunts cell division…

Melatonin sensitizes the system!

  1. Proliferation occurs at night for many cell types
  2. melatonin is ‘sensitizing’ these cells to process a big nutrient influx
  3. cortisol shuts down proliferation in the morning
  4. time to eat and get some sunlight!


Entraining central and peripheral clocks




Early to bed, early to rise, yada yada yada.  LIGHT & food in the morning.  No artificial light at night.

Can’t do these?

Light boxes in the morning can help.  Blue blockers at night.  Shift meals toward earlier in the day.

In general, most of these interventions function to “advance” the circadian phase, and Jane Plain wrote a great blog about how lithium also does this by inhibiting GSK-3b, which preserves REV-ERB alpha.

For what it’s worth, keep an eye on REV-ERB alpha; I think it’s one of the more important life-and-death circadian mediators.



lithium and GSK-3b


Circadian rhythms are more important than the carb vs. fat debate, imo.  Some people say we need to eat a certain way because we’ve been doing so for thousands of years.  Yeah, well, we’ve had circadian rhythms for BILLIONS of years!


disclaimer: I honestly don’t really like making the Evolutionary™ argument to support circadian rhythms simply because we have so many modern studies on it.  And who knows, our modern #context is so different from as little as 50 years ago… the Evolutionary™ argument is important, but I tend to put more weight on proper intervention studies.






Some of the modern studies (and/or blog posts about them):

Importance of bright light in the morning

Bright light in the morning attenuates the light-induced melatonin suppression at night (eg, Kozaki et al., 2015)

Blocking artificial light at night with hot Blue Blockers

Eat breakfast like a King, lunch like a prince, and dinner like a pauper: Afternoon Diabetes and Dawn PheNOMNOMNOM

Now, compare the studies on LIGHT, melatonin suppression, and meal timing with those on low carb vs. low fat:  circadian rhythms can be really messed up in the former studies, and no big difference in the latter… assuming #context is taken into account and we’re talking about real whole foods, duh.

That’s all, for now.

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