A Quick Afternoon Nap Can Be As Refreshing As Night-Time Sleep: Study

A quick afternoon nap can help the brain recover and put it back into a state where it is ready to learn -- effects were so far only known to occur after a full night's sleep, according to a new study.

Researchers at the universities of Freiburg in Germany and Geneva in Switzerland show that even a nap is enough to reorganise connections between nerve cells so that new information can be stored more effectively.

They explained that the brain is constantly active during the day -- new impressions, thoughts, and information are processed, strengthening connections between nerve cells (synapses).

While the strengthened synaptic connections are important for learning processes, they may also lead to saturation, lowering the brain's ability to learn further. Sleep helps regulate this excessive activity again -- without losing important information, the team said.

"The study shows that this 'synaptic reset' can happen with just an afternoon nap, clearing space for new memories to form," said study leader Dr. Christoph Nissen, who performed the study as medical director of the sleep centre at the department of psychiatry and psychotherapy at the Medical Center-University of Freiburg.

"Our results suggest that even short periods of sleep enhance the brain's capacity to encode new information," Nissen said.

Twenty healthy young adults were looked at -- they either took a nap (for 45 minutes on average) or stayed awake on two afternoons.

The team used non-invasive methods such as transcranial magnetic stimulation (TMS) and EEG measurements to draw conclusions about the strength and flexibility of the synapses.

Results showed that following a nap, the overall strength of synaptic connections in the brain was reduced, which the researchers said was a sign of the restorative effect of sleep.

At the same time, the brain's ability to form new connections was significantly improved, indicating that the brain was better prepared for learning new content than after an equally long period of wakefulness, the team said.

"The study reinforces the restorative effect of sleep for homeostatic and associative synaptic plasticity in the human cortex and demonstrates that even a short nap can promote this process," the authors wrote in the study published in the journal NeuroImage. 

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