Sleeping is ubiquitous in animals and humans and vital for healthful function therefore, sleep after training improves performance on various tasks in comparison to equivalent intervals of active wakefulness. But it’s been unclear so far whether that is a result of an energetic refinement of neural links or simply due to the absence of novel input. Researchers at the Medical Center – University of Freiburg have succeeded in demonstrating that sleeping is more than rest for enhancing performance. The findings that were published in the journal SLEEP provide important information for preparation phases of intensive training or learning.
“Sleep is irreplaceable for the recovery of the brain. It cannot be replaced by periods of rest for improved performance. The state of the brain during sleep is unique,” states Prof. Dr. Christoph Nissen, who headed the study as study team leader in the Department of Psychiatry and Psychotherapy in the Medical Center – University of Freiburg and is presently working at the University of Bern, Switzerland. In previous studies, Nissen and his group provided evidence for the notion that sleeping has a dual function for the brain: Unused connections are weakened and relevant connections have been strengthened.
In the present study, the investigators conducted a visual learning experiment with 66 participants. First, all participants were trained identifying certain routines. Afterwards, one group was alert watching videos or playing table tennis. The next team slept for a hour and the third group remained awake, but was in a darkened room without external stimulation and under controlled sleeping laboratory conditions. Not only did the team that slept perform considerably better than the team that was awake and active, but the sleeping group also performed significantly better than the group that was awake, but deprived from any outside stimulation.
The improvement in performance was linked to typical deep-sleep action of the brain, which has a significant function for the connectivity of neural cells. “This shows that it is sleep itself that makes the difference,” says co-study pioneer Prof. Dr. Dieter Riemann, head of the sleep lab at the Department of Psychiatry and Psychotherapy in the Medical Center – University of Freiburg. In control experiments, the Freiburg researchers ensured that fatigue along with other general factors had no impact on the results.
The analysis shows that sleeping cannot be substituted by rest during phases of intensive performance demands at work or in everyday life.