A Sleep Switch in the Brain

“Scientists Report the Discovery of a Brain ‘Switch’ That Brings On Sleep,” announced the headline of a New York Times article on January 12, 1996. The news marked the beginning of my quest to get to the bottom of my insomnia.

sleep switch“Scientists Report the Discovery of a Brain ‘Switch’ That Brings On Sleep,” announced the headline of a New York Times article on January 12, 1996. The news marked the beginning of my quest to get to the bottom of my insomnia.

“A master switching mechanism for sleep,” I read, “a tiny clump of cells deep in the brain,” in a structure called the hypothalamus. When the switch flipped on, the lights went out. I paused a moment to consider this fascinating tidbit, then read on.

The newly discovered sleep switch turned the lights out pronto. It should not be confused with the process that started people on the somnolent slide. That involved a different mechanism (undiscovered, as yet), a kind of “dimmer switch,” reporter Sandra Blakeslee wrote.

Could the sleep switch be a factor in my insomnia? I wondered. Unlike me, my husband had prodigious ability to fall asleep the minute he lay down or settled himself on an airplane. Was he endowed with a BMW model sleep switch and I, a rusty Ford?

In subsequent years it’s become clear that the sleep switch is one of the most important discoveries in sleep science to occur in the past few decades, and the way it functions does in fact affect people’s sleep.

A Sleep Regulating Center in the Brain

But the idea of a sleep center in the brain was originally proposed nearly a century ago in a context very different from the studies on rats and other lab animals that ultimately proved its existence. It came about during the epidemic of encephalitis lethargica (a kind of sleeping sickness that occurred concurrently with the influenza epidemic) that broke out in the United States and Europe toward the end of World War I. Encephalitis lethargica eventually sent half a million people to early graves.

Disrupted sleep was a common symptom. Some victims fell into a coma-like stupor that persisted for years and sometimes ended in death. A smaller number had the opposite problem. They became very tired but could barely sleep at all. (Sounds familiar, right?) Some of these people with severe insomnia also died.

Dr. Constantin Von Economo, a Viennese neurologist, treated thousands of patients afflicted with the disease. He also autopsied many of his patients who died. And he found a curious thing: in the brains of those who had fallen into a stupor, there was damage at the rear of the hypothalamus; the hypothalamus of those afflicted with insomnia was similarly damaged in the front.

What to make of this information? Von Economo proposed that there was a “sleep regulating center” in the hypothalamus. He was not far off the mark, as will be seen in Monday’s blog.