If You Sleep After You Study, You'll Remember More—Duh?

Effective Studying in Action (Image from Flickr, by Mrehan)

That sleep improves memory ought to be common sense knowledge, but apparently it is not, even after numerous studies have shown a strong correlation between sleep and memory (see Payne JD (2011) “Learning, memory and sleep in humans.” Sleep Medicine Clinics 6: 15–30 or Marshall L, Born J (2007) “The contribution of sleep to hippocampus-dependent memory consolidation.” Trends Cogn Sci 11: 442–450).

New research published in the Public Library of Science (PLoS) suggests that sleeping right after studying improves a student's ability to remember information. Subjects looked at related or unrelated words pairs either in the morning or evening and then were tested after 30 minutes, 12 hours, or 24 hours. The time of day had no effect on memory. At the 12 hour retest, memory was significantly better after a night of sleep versus a day of wakefulness for unrelated word pairs, but insignificant for related word pairs. However, at the 24 hour retest, the researchers found that memory was superior when sleep occurred right after learning rather than after a day of being awake.