People also used to wake up at 1, stay awake for a couple hours, and then go back to sleep. https://www.sciencealert.com/humans-used-to-sleep-in-two-shifts-may

People also used to wake up at 1, stay awake for a couple hours, and then go back to sleep. https://www.sciencealert.com/humans-used-to-sleep-in-two-shifts-maybe-we-should-again https://www.sciencealert.com/humans-used-to-sleep-in-two-shi...