Relearn Faster and Retain Longer

TLDR

Repeated practice and sleep both enhance long‑term retention, presumably through memory reactivation during on‑line or off‑line rehearsal. The study examined whether sleep‑dependent consolidation could reduce the practice time required for relearning. Forty participants practiced foreign vocabulary to perfect performance in two sessions 12 h apart, with half learning morning‑evening on the same day and the other half learning evening, sleeping, then morning the next day; retention was tested after 1 week and 6 months. Interleaving sleep between learning sessions cut practice time in half and yielded superior long‑term retention, making sleep between sessions a better strategy than sleeping only after learning.

Abstract

Both repeated practice and sleep improve long-term retention of information. The assumed common mechanism underlying these effects is memory reactivation, either on-line and effortful or off-line and effortless. In the study reported here, we investigated whether sleep-dependent memory consolidation could help to save practice time during relearning. During two sessions occurring 12 hr apart, 40 participants practiced foreign vocabulary until they reached a perfect level of performance. Half of them learned in the morning and relearned in the evening of a single day. The other half learned in the evening of one day, slept, and then relearned in the morning of the next day. Their retention was assessed 1 week later and 6 months later. We found that interleaving sleep between learning sessions not only reduced the amount of practice needed by half but also ensured much better long-term retention. Sleeping after learning is definitely a good strategy, but sleeping between two learning sessions is a better strategy.