My experience has been not as drastic, but I do use a similar approach and am seeing a gratifying level of results

- strict sleep schedule

- regular sun exposure, but not maxing

- cycling DHEA to keep cortisol levels manageable

- Testosterone higher from avoiding endocrine disruptors in food and synthetic materials

- supplementing magnesium, and cycling Glycine

- Focusing more on recovery (in early 40s, recovery is much slower), and strict calory intake - 10% higher than maintenance during bulking, 20% lower than maintenance during cuts.

- Training is medium intensity, low volume. 

If I were to guess, just based on my own experience your results are probably a synthesis of all of the different factors you are controlling for. I'd guess your training regimen, recovery strategy,  and calory intake are the lion's share, with everything else playing a supporting role.

https://image.nostr.build/c5ba2d2074f2d32c9952538cc832078637d6319a3e4b88df136b44ceb1d248b6.jpg 

 Yeah I think getting rid of excess volume + big focus on recovery and food has been key

I've read some papers on the circadian aspects of muscle growth 

I'd love to see a control study because no one has measured this