Bright light exposure upon waking
Johnson relies on this because his 4:30 a.m. wake-up means no sunlight. By using a bright lamp, he simulates the dawn signal that anchors his body’s internal clock. This sets up better sleep at 8:30 p.m. and daytime performance. He also suggests that those who can get natural sunlight should time their walk when UV is low to protect skin.
Light through the eyes stimulates melanopsin-containing retinal ganglion cells, which project to the SCN, suppressing melatonin and elevating cortisol in a timed manner, thus entraining the sleep-wake cycle.
He does this every morning in his bathroom.
I turn on this 10,000 lux light first thing. It helps mimic natural sunlight and signal to my body that it's daytime.

