By Stephen Beech
Afternoon naps are good for the brain – and improve the ability to learn, according to new research.
Taking a short siesta is enough to reorganize connections between nerve cells so that new information can be stored more effectively, say scientists.
Until now, those effects were only known to occur after a full night’s sleep.
The new study by researchers from the University of Freiburg in Germany, and the University of Geneva in Switzerland, shows that even a short period of sleep of up to 45 minutes can relieve the brain and put it back into a state of readiness to learn.
Grabbing 40 winks could be particularly beneficial in situations involving a high work load, according to the researchers.
Study leader Professor Christoph Nissen said: “Our results suggest that even short periods of sleep enhance the brain’s capacity to encode new information.”
He explained that the brain is constantly active during the day with new impressions, thoughts, and information being processed, strengthening the connections between nerve cells, known as synapses.
Nissen says the strengthened synaptic connections are an important neural basis for learning processes.
However, they also lead to saturation, so that the brain’s ability to learn further decreases over time.
But sleep helps to regulate excessive activity again – without losing important information.
Nissen said: “The study shows that this ‘synaptic reset’ can happen with just an afternoon nap, clearing space for new memories to form.”
Dr. Kai Spiegelhalder, of the University Medical Center Freiburg, said: “The study helps us understand how important even short periods of sleep are for mental recovery.
“A short nap can help you think more clearly and continue working with concentration.”
The research team examined 20 healthy young adults who either took a nap or stayed awake on two afternoons.
The afternoon nap lasted on average 45 minutes.
Since direct measurements on synapses in healthy humans are not possible, the researchers used established, non-invasive methods such as transcranial magnetic stimulation (TMS) and EEG measurements to draw conclusions about the strength and flexibility of the synapses.
The results, published in the journal NeuroImage, showed that after the nap, the overall strength of synaptic connections in the brain was reduced – a sign of the restorative effect of sleep.
At the same time, the brain’s ability to form new connections was “significantly” improved.
The brain was therefore better prepared for learning new content than after an equally long period of wakefulness, according to the researchers.
They say the study provides a biological explanation for why people often perform better after an afternoon nap.
Nissen said a nap could be used to maintain performance, especially in professions or activities that require a high level of mental or physical performance – such as in music, sports, or safety-critical areas.
He added: “An afternoon nap can sustain performance under high demand.”
However, the research team emphasised that occasional sleep problems do not automatically lead to a decline in performance.
Nissen said that in chronic insomnia disorder, in particular, sleep-wake regulatory systems are essentially intact; rather, worries and unfavourable sleep-wake patterns dominate.
He says that in such situations, cognitive behavioural therapy for insomnia is more useful than sleeping pills, as the latter can disrupt the brain’s natural recovery processes and lead to dependence.
