Overactive neurons in the brain contribute to the poor sleep quality that often accompanies aging.

Sleep is crucial for maintaining cognitive health throughout the lifespan. However, sleep quality often declines with age. Findings from a new study in mice suggest that overactive hypocretin neurons contribute to the poor sleep quality that often accompanies aging.

Hypocretin, also known as orexin, is a type of neuropeptide – a signaling molecule composed of short amino acids and produced by neurons. Hypocretin is produced primarily in the hypothalamus, where it is involved in aspects of wakefulness and appetite.

The investigators used optogenetics to study and record the activity of hypocretin-producing neurons in the brains of young and old mice. Optogenetics is a research technique that allows scientists to switch a neuron’s activity on or off using light and genetic engineering.

They found that older mice had nearly 40 percent fewer hypocretin-producing neurons than younger mice. The remaining neurons, which were more excitable than those present in younger mice, triggered wakefulness and poor sleep. The investigators attributed these changes in the neurons to age-related loss of potassium channels (which regulate neuronal excitability) in the older animals' brains.

These findings suggest that poor sleep that accompanies aging may be due to intrinsic changes in the number and activity of hypocretin-producing neurons, providing potential targets for sleep therapies in the future. Learn about some of the effects of age-related sleep loss in this episode featuring Dr. Matthew Walker.

• Link to study abstract.