Wake Up to the Dark

the Author walks the path toward a new appreciation of the night.

- By Clark Strand

In the early 1990s, a researcher at the National Institute of Mental Health in Bethesda, Maryland, took a group of ordinary subjects offall forms of electrical lighting for one month in order to determine if modern humans still carried within them the traces of a prehistoric mode of sleep. At week three, the subjects in Dr. Thomas Wehr’s study all began waking after four hours of sleep to a two-hour period of quiet rest before falling asleep again for another four. During the gap between those two sleep segments, the subjects experienced a condition of profound peace.Wehr could find no precedent for this in the scientific literature. It was a state having “an endocrinology all its own.”

Eventually, Wehr discovered that prolactin was involved. Prolactin is the hormone that keeps mammals still and at rest when they are asleep. Its levels also rise in nursing mothers when their milk lets down, keeping them calm and attentive to their babies’ needs. Nowadays it is called “the attachment hormone” because of its role in the bonding of infants with their mothers.

The prolactin levels in Wehr’s subjects should have fallen when they woke in the middle of the night. But they didn’t. They remained stable throughout that two-hour period of wakeful, quiet rest.

The only thing Wehr could find that was comparable to those two hours was the state experienced by advanced meditators. But there hadn’t been any meditators in his study. The participants were simply ordinary people who had agreed to go off artificial lighting for one month.