Top performers wake at 7:30 AM in time zones with an hour of daylight savings time.
Diminishing returns can be had if one bothers to optimize further.
Different people need a different number of 90 minute sleep cycles:
| Sleep Hours | Population |
|---|---|
| 9 | 10% |
| 7.5 | 70% |
| 6 | 20% |
| 4.5 | 1% |
The earth spins with a daily 3 millisecond variance. The planet’s clock. In the morning, after the dust has settled over night and the air is clean, the cool air with water vapor, the direction of the earth’s spin and temperature gradient relative to the incoming rays, and seeing light after it being dark for some time, all leads to morning light being the most blue and evening light being the most orange.
Light enters the eye and is absorbed by three types of photosensitive cells. Rods for low-light, cones for color and detail, and ganglion for sending timing signals to the brain. Ganglion are mostly found in the lower eye meaning that they are most sensitive to overhead light.
This information is sent to the body’s timer, the Suprachiasmatic Nucleus (SCN) which records it on a three day ring buffer. The information is averaged over a 24 cycle.
The SCN is most sensitively after waking and also to powerful blue light found in the morning light.
Outdoor light is far brighter (a higher lux) than indoor light. Indoor light might be brighter at a given point but outdoor light is much ambiently brighter overall. Outside, the eye balances so it doesn’t seem so bright even though it is.
The SCN regulates the body’s functions, using it’s hardware for multiple purposes depending on the time of day:
And everything else that the body needs a timer for, such as: