Second Sleep
"Numerous other studies have shown that splitting sleep into two roughly equal halves is something that our bodies will do if we give them a chance. In places of the world where there isn't artificial light -- and all the things that go with it, like computers, movies, and bad reality TV shows -- people still sleep this way. In the mid-1960s, anthropologists studying the Tiv culture in central Nigeria found that group members not only practiced segmented sleep, but also used roughly the same terms of first sleep and second sleep. ... [Yet] almost two decades after Wehr's study was published in a medical journal, many sleep researchers -- not to mention your average physician -- have never heard of it. When patients complain about waking up at roughly the same time in the middle of the night, many physicians will reach for a pen and write a prescription for a sleeping pill, not realizing that they are medicating a condition that was considered normal for thousands of years. Patients, meanwhile, see waking up as a sign that something is wrong."
I've been obsessed with sleep since a young age, mostly because I can't remember when was the last time I got what felt like a restful, solid night of good sleep.
Recently I read Dreamland by David K. Randall and ran into this passage. This is an experience I can relate to. I often joke that I don't go to sleep but that instead I take two or three naps a night with reading intermissions.