Neuroscience We may now know which neurons dictate when it is time to go to sleep Chris Simms RESEARCHERS have identified specific groups of neurons in the brains of mice that are activated after the rodents have been awake for a long time, driving them to sleep. If a similar system exists in humans, it could be targeted to help improve treatments for some sleep disorders. What drives the urge for us to feel tired and fall asleep? Inside the brain, several neural circuits regulate sleep and wakefulness, including neurons in the hypothalamus that act like a switchboard to control the process. …