An international team of neuroscientists led by the Jülich Research Center in Germany has studied the brain's response to lack of sleep. The results indicate that just one sleepless night causes structural changes similar to 1–2 years of aging. Scientists tested whether they are reversible, and also considered the impact of periodic and chronic sleep deprivation on a person.

The study used the brainageR machine learning algorithm. To do this, AI was taught to determine the chronological age of people based on MRI images of three thousand people.

The experiment itself involved 134 healthy adults from 19 to 39 years old, who were divided into four groups:

with complete lack of sleep - these participants spent more than 24 hours without a night's rest;
with partial sleep deprivation - they slept three hours a night;
with chronic sleep deprivation - slept for five hours every night for five days,
the control group, where people slept for eight hours a day.

After each night, the participants had MRI scans to compare what their brains looked like before and after the sleep deprivation. The three groups in which the volunteers had their sleep restricted also received a night of restorative sleep, after which they were examined.

The most significant changes were recorded in people from the first group.

“We have consistently observed that total sleep deprivation increased brain age by 1 to 2 years in just one night. In contrast, brain age did not change significantly with either partial or chronic sleep restriction,” according to a study published in the journal Neuroscience.

Acute generalized sleep loss alters brain morphology in a direction similar to aging in younger participants. But these changes are reversible with the help of restorative sleep, the scientists conclude.

The team's findings are consistent with previous studies that have shown that several types of changes occur in the human brain without sleep, including in fluid distribution and gray matter volume.

The authors note that the study was very small and short-term, with even a chronic condition observed for only five days. This may be why the effect was found only in the total sleep deprivation group, and one night of normal sleep was enough for the brain to recover. If there are more participants, the scientists expect to see effects in other groups as well, such as several months of “aging” of the brain.