Neurosciences Zurich researchers observe pupils of sleeping people for the first time
For the first time, researchers have observed the pupils of sleeping people over several hours. They discovered that the size of the pupil constantly fluctuates, even during sleep.
05.03.2025, 08:49
SDA
"These observations contradict the previous assumption that the level of arousal during sleep is fundamentally low," said study leader Caroline Lustenberger from ETH Zurich in a press release issued by the university on Wednesday. This is because the dynamics of the pupils reflect the state of arousal of the brain.
According to ETH Zurich, the pupil fluctuations during sleep show that the brain is constantly alternating between a higher and lower level of activation, even during sleep. The results were published in the journal "Nature Communications".
Sleeping with one eye open
Scientists at ETH Zurich have developed a new method for looking under the eyelids of sleeping people. They stuck a special transparent plaster over an open eye. The researchers' biggest concern was that the test subjects would not be able to sleep with their eyes open. "But in a dark room, most of them forget that their eyes are still open and can still sleep," explained the first author of the study, Manuel Carro Domínguez, in the university's press release.
According to the researchers, understanding pupil dynamics during sleep could provide important information for the diagnosis and treatment of sleep disorders and other diseases.
The technology for monitoring pupils during sleep will also be used outside the sleep laboratory in the future. According to ETH Zurich, it could help hospitals, for example, to monitor the awakening of coma patients or to diagnose sleep disorders more accurately.
