The Seven Day Cycle
You have heard me talk about circadian rhythms before (I hope). These are the internal clock that our body, hormonal systems and organs run off. Our morning and evening routines signal to these clocks and help them work well (partly why its critical that you are consistent with your routines).
Beyond circadian rhythms our bodies have a natural 7 day cycle. This natural 7 day cycle is bound up in all of biology. Everything that has a body, from insects to fish to mamals, has a natural built in, 7 day cycle. Its genetics and called the “Circaseptan rhythm”. *We also have our monthly and yearly cycles, and even light and dark response cycles know as “diurinal rhythm”.
Circaseptan means “about every seven days”. What you have always intuitivly known… some days are better than others for certain things… turns out to be biological fact.
Your body has a natural daily cycle and a natural weekly cycle, along with your monthly cycle.
Dr David Ellis, from the University of Lincoln’s School of Psychology, was quoted in a 2015 paper saying;
“The seven day weekly cycle is repeated for all of us from birth, and we believe this results in each day of the week acquiring its own character.”
Once you undertand circaseptan rhythms, it can change evrything.
For example, cortisol to DHEA ratio is highest on Mondays. Meaning, cortisol is generally higher on Monday, compared to your DHEA. Because Mondays are higher is stress. So nutrition for Mondays may require more stress adaptions, because of its impact on our adrenals and immune system. This would be higher amounts of polyphenols in the early part of the day (think blueberries, dark chocolate and good coffee), paired with a whey protein or good quality animal products. This helps support immunity, hormones and boosts vitamin B production later in the day, to counter stress. This also drives production of serotonin precursors, to further counter stress. And then we take some EPA (Krill) around lunch, which helps further spin down stress induced cortisol in the evening and at night, and can help you from coming home and stress eating.
This same protocol can be followed again on Wednesday, as it is percieved to be the second most stressful day of the week. (Tuesday too in my opinion).
Here are a few science established facts regarding the natural 7 day cycle;
Monday and Tuesday are the healthiest days of the week based on this paper.
Research on sodium balance, has shown that sodium retention works in a seven day cycle, directly related to cortisol. That also works independently of sodium intake! Meaning that even without over consumption of sodium, you can retain fluid, based on your cortisol levels.
Weight loss seems to hit its lowest point on Fridays.
Research on HRV (heart rate variability) has shown pulse rates work in a seven day cycle.
Tuesday night may be the best night for good sleep. Because salivary levels of melatonin secretion have a seven day cycle. Peak melatonin is Tuesday and lowest melatonin is Saturday. This may be why many of us have a worse sleep on refeed day (Saturday), along with the food interferences.
Epileptic seizures have been shown to occur in seven day cycles.
Cortisol to DHEA ratio is highest on Mondays. Stress and depression also peak on Monday.
Plasma cortisol levels have been shown to be lowest on Thurdays. Meaning Thursday can be the best day for enjoyment for most people.
Sundays are the second lowest days for plasma cortisol levels. Making Sundays the best day for calmness and enjoying the day (and setting yourself up for a good week).
Chrono-immunology.
Circaseptan is being applied to medicine too. Chrono-immunology is the practive of timing and dosing of treatments, to specific times and days. Which can make up to 100% difference in effectiveness. For example; experiments with heart failur e patients suggest a strong seven day rhythm. The highest likelihood of heart attack is Wednesday afternoon.
Interesting right?!