Sleep facilitates the storage of new information in the hippocampus – the region of the brain responsible for the formation and consolidation of short-term memories. Poor sleep, however, inhibits the brain’s ability to form memories. Findings from a new study demonstrate that two nights of recovery sleep after a period of sleep deprivation restores hippocampal activity but not the ability to form memories.

Sleep deprivation increases a person’s risk of developing many chronic illnesses, including cardiovascular disease, kidney dysfunction, hypertension, diabetes, stroke, obesity, and depression. More than a third of all adults living in the United States report having poor sleep habits.

The study involved 39 healthy adults who participated in a controlled in-laboratory sleep protocol. Each of the participants experienced one night of sleep deprivation followed by two consecutive nights of recovery sleep. The authors of the study used standard recognition tests to assess the participants' ability to form memories at baseline and every day thereafter. They used functional magnetic resonance imaging (fMRI) to assess the participants' hippocampal functional connectivity at baseline, after sleep deprivation, and after recovery sleep.

After a single night of sleep deprivation, the participants' memory performance was markedly worse. Similarly, the fMRIs revealed that the participants' hippocampal connectivity was impaired in several regions of the brain associated with memory formation.

After two nights of recovery sleep, hippocampal connectivity was restored, but memory performance was still impaired. These findings suggest that a person needs more than two nights of recovery sleep to restore memory function after just one night of sleep loss.

Other studies have demonstrated the effects of sleep deprivation on academic performance. Watch this clip in which sleep expert Dr. Matthew Walker describes the role that sleep plays in learning and new memory formation.

• Link to full study.