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Researchers at the Medical Center - University of Freiburg demonstrate for the first time that active recovery processes take place in the brain during sleep that cannot be replaced by rest / Findings relevant for optimal performance

Sleep is ubiquitous and vital in the animal kingdom. Its importance for the stabilization and reinforcement of brain performance has also been known for a long time. However, it was previously disputed whether this is primarily due to the fact that the brain does not have to process new stimuli during sleep or whether active neuronal processes weaken unimportant information and connections in the brain. Researchers at the Medical Center - University of Freiburg have now succeeded in demonstrating that sleep is more important for improving cognitive abilities than the absence of external stimuli. The findings, which were published in the journal Sleep on January 6, 2021, provide important information for planning intensive learning phases such as A-levels or final exams.

"Sleep is irreplaceable for brain recovery. It cannot be replaced by rest periods to improve performance. We show this clearly for the first time in this study. The state of the brain during sleep is unique," says Prof. Dr. Christoph Nissen, who led the study as research group leader at the Department of Psychiatry and Psychotherapy at the Medical Center - University of Freiburg and now works at the University of Bern, Switzerland. In previous studies, Nissen and his team were able to show that sleep has a dual function for the brain: Unnecessary connections are weakened and relevant connections are strengthened.

In the current study, the researchers conducted a visual learning experiment with 66 test subjects. First, all participants practiced distinguishing certain patterns. Afterwards, one group was awake and watched videos or played table tennis. One group slept for an hour and the third group stayed awake, but was in a darkened room without external stimuli and under controlled sleep laboratory conditions. The group that had slept not only performed significantly better afterwards than the group that was awake and active. The passively awake group also outperformed them. The improvement in performance was linked to typical deep sleep activity in the brain, which has an important function for the strength of the connections between nerve cells. "This shows that it is sleep itself that makes the difference," says co-study leader Prof. Dr. Dieter Riemann, Head of the Sleep Laboratory at the Department of Psychiatry and Psychotherapy at the Medical Center - University of Freiburg. In control experiments, the Freiburg researchers ensured that tiredness and other general factors had no influence on the result.

The study shows that sleep cannot be replaced by rest during phases of intensive performance requirements at work or in everyday life.

Original title of the study: Sleep is more than rest for plasticity in the human cortex

DOI: 10.1093/sleep/zsaa216

Link to the study: https://academic.oup.com/sleep/advance-article-abstract/doi/10.1093/sleep/zsaa216/6047280

Contact:
Prof. Dr. Christoph Nissen
Research Group Leader
Department of Psychiatry and Psychotherapy
Medical Center - University of Freiburg
Christoph.Nissen@upd.ch