A new US study suggests that grabbing forty winks at lunchtime may aid the memory, providing the facts have been well learned in the first place.

‘Declarative memory’ refers to textbook-style learning, as opposed to skill-based learning which is called ‘procedural memory’. According to researchers at Harvard Medical School’s Centre for Sleep and Cognition, the sleeping process appears to help cement declarative memories, thereby making them simpler to recollect. Lead researcher Matthew Tucker, a Harvard postdoctoral fellow, commented, ‘Sleep appears to have an impact on what is learned well, but not so much when one is not motivated to learn’.

The study involved 33 people being trained in specific declarative memory tasks. Post-training, 16 participants had a short sleep, and the remaining 17 stayed awake watching a movie. All of the participants were then tested later in the day in tasks which included memorising words, a maze and a line drawing.

The researchers found that the group which took a nap displayed improved performance in the declarative tasks when compared to the group that stayed awake. This effect was only noticeable, although, in those who had thoroughly learned the task in the first place. ‘The nap group performed better overall than the awake group, but the difference wasn’t significant’ Tucker said, ‘However, when we looked at individual performance during training, we found those who did better during training benefited from napping’.

Interestingly, individuals were found to perform well in only one task rather than in all three; ‘There is likely a basic level of learning that has to be attained before sleep can have an impact on performance’ Tucker concluded’.