Have we found the brain’s sleep switch?

In Massachusetts, building on research from two decades ago, Beth Israel Deaconess Medical Center researchers have demonstrated that, at least in mice, a region of the hypothalamus called the ventrolateral preoptic nucleus is essential to normal sleep.

Working with genetically engineered mice, the team artificially activated the VLPO neurons using several different tools. In one set of experiments, the scientists activated the neuron cells using a laser light beam to make them fire, a process called optogentics. In another test, the team used a chemical to selectively activate the VLPO neurons. In both cases, activating these cells profoundly drove sleep.

The results confirmed the colleagues’ earlier findings that these neurons are active during sleep and that damage to them causes insomnia – as seen in their subsequent work with laboratory animals and, in 2014, in older people who have lost cells of the VLPO as part of the natural aging process.