Scientists Find Brainstem Neurons That Turn Wakefulness Into Sleep Pressure

Researchers have identified two groups of brainstem neurons in mice that become steadily more active the longer the animals stay awake, helping convert prolonged wakefulness into mounting pressure to sleep. The study, led by Professor Alex Schier at the Biozentrum, University of Basel, with scientists from Beth Israel Deaconess Medical Center and Auburn University, was published in Nature.

The team mapped brain activity in mice during normal sleep and wakefulness, forced sleep deprivation, and recovery sleep, and identified two neuronal populations within one brainstem region: GABAergic neurons and serotonergic neurons. Both grew increasingly active the longer the mice stayed awake, then quieted after sleep began.

To test whether the neurons merely tracked wakefulness or actively caused sleep, the researchers experimentally altered their activity. Activating both populations made mice sleep longer and more deeply, resembling normal recovery sleep; inhibiting them had the opposite effect, and the mice slept far less while remaining alert.

When both populations were inhibited over an extended period, the mice slept about 70% less than usual, yet most did not show the severe behavioural problems normally associated with sleep deprivation — suggesting sleep duration and sleep need may be more separable than previously assumed.

First author Dr William Joo said future studies could examine how these neurons interact with the rest of the brain and how sleep drive arises at the molecular level, potentially revealing ways to build resilience to long-term sleep loss.