In my final year of university, with exam deadlines looming and time increasingly fleeting, I considered recording some of my notes and playing them over while I was asleep. The concept of effectively gaining 6 extra hours of revision was appealing, but the idea didn't stick - it took too long to record the information and the noise stopped me from sleeping in the first place. And the whole thing had a vague hint of daftness about it. But a new experiment suggests that the idea actually has some merit, showing that you can indeed strengthen individual memories by reactivating them as you snooze.
Sleep is a boon to newborn memories. Several experiments have shown that sleep can act as a mental cement that consolidates fragile memories into stable ones. But John Rudoy from Northwestern University wanted to see if this process could be taken even further by replaying newly ...