Book Review of "The Circadian Code" by Satchin Panda, PhD, 2018

For anyone who has been hyper focused on diet and exercise modifications, this book is a great reminder that not just what you do, but when you do it, can be vitally important! The author does a nice job of providing evidence-based suggestions to harness the power of timing. The book recommends tracking bedtime, eating times (first and last of the day), screen time (last time of the day) and exercise times. It recommends (page 61-62):

• Consistency between days

• 7 to 9 hours of quality sleep (Do you need an alarm clock? Are you tired in the morning?....more quality sleep is probably indicated!)

• Less than a 12 hour eating window

• At least 3 hours between last eating and bedtime.

One thing that might be surprising to many people is that the various organs and systems have their own circadian rhythms. I first heard about this in the context of eastern medicine philosophies (such as ayurveda and chinese medicine), but I was blown away by all of the evidence of this that was presented in the book. For example, on page 175, the author mentions that saliva secretion drops at night, which promotes sleep, but eating late at night can cause excess stomach acid production and without the saliva buffer in the esophagus and mouth, acid reflux is exacerbated. Thus, one of many links between eating time and acid reflux! This is one of so so many examples. Another interesting point was his discussion of the link between dysregulated circadian rhythm and the development of Type II Diabetes. In fact, I was a little shocked at the mention that just one week of reduced sleep can put someone in the prediabetic range (page 197)!

One of my personal takeaways from reading this book was renewed confidence in eating breakfast. I’ve struggled with fasting through breakfast…and whether to fast though breakfast seems to be controversial among experts. So it’s been a point of confusion for me. I am now testing how eating earlier and fasting earlier at night affects my Lumen device scores, energy levels and symptoms. A beautiful illustration of the relationship between blood glucose and timing of meals is found on page 197. It shows that blood glucose increases more and stays elevated longer when we eat the same meal later in the day, thereby providing evidence that we may be more insulin sensitive earlier in the day…another argument to balance your blood sugar early and forgo that bedtime snack!

Aside from our own tissues, the microbes in our gut also follow circadian rhythms and with this the immune system, which interacts with these microbes, good and bad, also follows a circadian rhythm when it is well regulated. Chronic inflammation occurs when the on and off rhythms of the immune system become dysregulated or stuck on all the time (page 208).

Implications of timing for various medical interventions, such as medications, surgery and chemotherapy, was also highlighted. For example, a study mentioned on page 211 notes that RA patients who took an extended-release version of prednisone had improved morning stiffness than those who took an immediate release at bedtime. The author notes that “the tolerability of nearly 500 medications improves by up to fivefold when they are matched to circadian scheduling.” This sparked my curiosity about all of the easily untapped gains that could be made in modern medicine if medical providers paid attention to timing of medical interventions.

As someone who has had a long, somewhat strained history with the ketogenic diet, I was comforted to hear the author say that many of the benefits of being in ketosis (such as neurogenesis) can be reaped through TRE (time restricted eating) of 8 to 10 hours (page 230). In fact, TRE was a major theme of the book and one of my greatest takeaways.

Unfortunately, modern technology often works against us in balancing our circadian clock! With 24-7 access to streaming and media, late night lighting, non-traditional work schedules, etc., it’s no wonder that people struggle with the effects of dysregulated circadian rhythms, but before reading this book, I was not aware of the vast implications and how important it is to restore these rhythms.

Note that reviewed books have not been fact checked against scientific literature and that I do not endorse information or recommendations given in reviewed books. The book reviews serve to provide my personal takeaways and spawn potential interest in the subject matter for future research, follow-up or reading.