1. light (change of day and night); 2. temperature; 3. the use of drugs; 4. food intake regime; 5. Atmosphere pressure; 6. rest regimen.
This scheme is surprisingly similar to the ancient Chinese scheme of the movement of qi energy, when at a certain time this or that organ manifests its activity.
The time from 10 pm to 4 am can be considered ideal for sleeping. At this time, the production of melatonin is at its maximum, and cell regeneration is more active.