Biphasic sleep in adults can involve one long sleep bout at night and a shorter bout during the day, timed to coincide with natural drops in alertness.

“A biphasic sleep pattern can include a siesta-like nap during the day, typically between 1 PM and 4 PM, which aligns with natural drops in alertness.”

“time it based on this sort of post pral drop you will know yourself everyone has fallen prey to it you know W it's usually around about 3 4 p.m. that I do start to feel this decline or it's around 1 p.m. try to match it in accordance with that”

“somewhere between about two to four p.m both you and i will have this kind of drop in our physiological alertness in our physiological level of brain activity”

“somewhere between about two to four p.m both you and i will have this kind of drop in our physiological alertness in our physiological level of brain activity in other words as if as a species we're almost pre-programmed to have this enforced dip in our alertness”