Sleep window and next-day recall

Source summary

A university team wanted to know whether a protected sleep window after studying is linked to next-day recall. They recruited 64 first-year students ages 18–19 from one campus (38 women, 26 men, as the form recorded). All had slept at least six hours the previous night, by self-report. Students were randomly assigned to one of two conditions. In the protected-sleep condition, phones were collected at 23:00 and returned at 07:00; lights were dimmed. In the unrestricted condition, phones stayed with the student; the lab did not control light. Both groups studied the same 24 invented word pairs for 20 minutes at 21:30. The next afternoon, all students wrote as many pairs as they could (cued recall: first word given). Mean pairs recalled: protected-sleep 17.2, unrestricted 12.4. The protocol asked students to sign a form describing the purpose (‘how evening routines relate to memory’), the right to stop, and that phone collection was temporary. After testing, researchers explained the two conditions, returned phones, and offered a rest room. They also noted that a staff member, not other students, saw individual scores (confidentiality). Two students in the unrestricted group mentioned later that they had drunk caffeine after 22:00; the team did not exclude them.

• — Sample: 64 first-years at one campus, ages 18–19.
• — Design: random assignment to protected sleep vs unrestricted phones/light.
• — DV: cued recall of 24 word pairs the next afternoon.
• — Means: 17.2 vs 12.4 pairs.
• — Ethics mentioned: informed consent form, right to stop, debriefing, confidentiality of scores.
• — Limit: caffeine in two unrestricted students; one campus; self-report of prior sleep.