Why Does Sleep Help You Remember?

It's the night before a big test: cram until 3 a.m., or close the books and go to bed? Why does sleep help you remember? The tiny 1924 study that started it all, how the hippocampus holds fresh memories like a notepad before they're woven into the cortex, the slow waves, spindles and ripples of deep sleep that seem to replay the day, the 2007 experiment where a rose scent released during deep sleep improved memory, why a sleepless night makes it harder to learn new things, and what naps can (and can't) do. What you can do: 1. Let sleep follow your studying instead of pulling an all-nighter. In one study, people who learned new words, slept, and reviewed them the next morning needed about half as much practice, and remembered more months later. 2. Keep your sleep regular. Students with steadier sleep schedules tended to get better grades (a link, not proof). Experts recommend at least 7 hours a night for adults and 8 to 10 for teenagers. 3. Don't count on learning from recordings while you sleep. A sleeping brain may pick up very simple links, but there's no good evidence you can study for a test that way. Chapters 0:00 The night before the test 0:15 An old discovery 1:03 The night shift 1:48 Ready to learn 2:18 What you can do 3:05 Recap 3:20 Check yourself 3:54 Wrap-up Sources & further reading • Rasch B. & Born J. (2013). About Sleep's Role in Memory. Physiological Reviews, 93(2): 681–766 (includes Jenkins & Dallenbach's 1924 study): https://www.ncbi.nlm.nih.gov/pmc/arti... • Diekelmann S. & Born J. (2010). The memory function of sleep. Nature Reviews Neuroscience, 11(2): 114–126: https://doi.org/10.1038/nrn2762 • Rasch B. et al. (2007). Odor Cues During Slow-Wave Sleep Prompt Declarative Memory Consolidation. Science, 315(5817): 1426–1429: https://doi.org/10.1126/science.1138581 • Yoo S.-S. et al. (2007). A deficit in the ability to form new human memories without sleep. Nature Neuroscience, 10(3): 385–392: https://doi.org/10.1038/nn1851 • Mednick S. et al. (2003). Sleep-dependent learning: a nap is as good as a night. Nature Neuroscience, 6(7): 697–698: https://doi.org/10.1038/nn1078 • Lahl O. et al. (2008). An ultra short episode of sleep is sufficient to promote declarative memory performance. Journal of Sleep Research, 17(1): 3–10: https://doi.org/10.1111/j.1365-2869.2... • Sleep Foundation. Napping: Benefits and Tips: https://www.sleepfoundation.org/sleep... • Gais S., Lucas B. & Born J. (2006). Sleep after learning aids memory recall. Learning & Memory, 13(3): 259–262: https://doi.org/10.1101/lm.132106 • Mazza S. et al. (2016). Relearn Faster and Retain Longer: Along With Practice, Sleep Makes Perfect. Psychological Science, 27(10): 1321–1330: https://doi.org/10.1177/0956797616659930 • Phillips A.J.K. et al. (2017). Irregular sleep/wake patterns are associated with poorer academic performance and delayed circadian and sleep/wake timing. Scientific Reports, 7: 3216: https://doi.org/10.1038/s41598-017-03... • Okano K. et al. (2019). Sleep quality, duration, and consistency are associated with better academic performance in college students. npj Science of Learning, 4: 16: https://doi.org/10.1038/s41539-019-00... • Watson N.F. et al. (2015). Recommended Amount of Sleep for a Healthy Adult. Journal of Clinical Sleep Medicine, 11(6): 591–592: https://doi.org/10.5664/jcsm.4758 • American Academy of Sleep Medicine. Teen Sleep Duration Health Advisory: https://aasm.org/advocacy/position-st... • Züst M.A. et al. (2019). Implicit Vocabulary Learning during Sleep Is Bound to Slow-Wave Peaks. Current Biology, 29(4): 541–553: https://doi.org/10.1016/j.cub.2018.12... Researched and fact-checked against the sources above. Whys of Everything: Short answers to big little questions. Subscribe for new animated explainers every week. #sleepandmemory #studytips #memoryconsolidation