The human autonomic nervous system is better at activating and staying alert than shutting down to sleep on demand.

“because of this asymmetry in the autonomic nervous system where it's much easier for us to push, and to delay our sleep time than it is to accelerate our wake-up time.”

“But it's very hard to make ourselves fall asleep. And so there's a sort of asymmetry to the way our autonomic nervous system, which governs this alertness, calmness thing, the sympathetic and parasympathetic nervous system, there's an asymmetry there where we are more easily able to engage wakefulness and drive wakefulness.”

“human beings and probably, most species, are better able to activate and stay alert than they are to shut down their nervous system and go to sleep on demand.”

“there's this asymmetry in the autonomic nervous system where it's much easier for us to push and to delay our sleep time than it is to accelerate our wakeup time”