Answer: C
It splits into two blocks with one to two hours awake in between
Verified · Wikipedia, Scientific American, A. Roger Ekirch, At Day's Close
In 1992, psychiatrist Thomas Wehr kept seven men in 14 hours of darkness every night, for a month. By week four their sleep split into two four-hour blocks, an hour or two awake between. Historian Roger Ekirch found the same pattern in pre-industrial Europe.
If you wake in the middle of tonight, skip the phone. Lie still for twenty minutes and let the second stretch of sleep come back on its own. Ask the friend who always complains about waking at 3 a.m. what that really means, they probably have no idea it was the normal way to sleep for centuries.
