I observed some interesting things regarding health on my recent international trip. Basically, I could see the process of my "How to Lose Weight" page in reverse.
Due to flight schedules, I ended up with less sleep than usual. And so then I noticed going down this path:
Get less sleep
Start to eat when not hungry
Find it difficult to know when full
Crave junk food
Have less motivation to move around
All of this is a one-way ticket to weight gain, and it was all set in motion by the lack of sleep! I felt like I gained a pound or two over the weekend there, though obviously it will reverse now that I'm back to normal circumstances.
I still view sleep/darkness time as the bedrock of health. This "experiment" only further confirmed my thoughts.