Longer NREM periods in a short nap negatively correlate with subsequent encoding performance, possibly due to sleep inertia¶

Claim · All claims
Evidence · 1 study · causal r2 · q2 · i3 large
Currency · newest study 2025 · not yet checked against its sources · not reviewed by a person

Subclaims¶

q2 i3 Within the Nap group, the percentage of NREM sleep correlated negatively with test performance (r = −0.46), as did spindle power density (r = −0.41). → Vidal 2025

Evidence¶

Vidal 2025¶

Vidal, V., Pretel, M. R., Capurro, L., Tassone, L. M., Moyano, M. D., Malacari, R. G., Brusco, L. I., Ballarini, F. M. & Forcato, C. (2025). Short naps improve subsequent learning in a high school setting. npj Science of Learning 10:15. https://doi.org/10.1038/s41539-025-00307-4

q2 · i3 · causal · r2

Pearson correlation analysis of EEG-recorded nappers (n = 26) relating sleep-stage percentages and band power densities to test scores. The article found "a significant negative correlation between the percentage of NREM sleep and performance" (r = −0.46) and a negative spindle correlation (r = −0.41).

"Surprisingly, we found a significant negative correlation between the percentage of NREM sleep and performance (Fig. 2a, r = −0.46, p = 0.015) and a negative correlation between spindles mean power density and performance (Fig.2b, r = −0.41, p = 0.034)"

Discussion¶

Related Claims¶

• Exploratory analysis finds moderate-magnitude correlation between central fast spindle density and retention of no-feedback retrieval-practice items — related
• SWA, slow-oscillation and delta power density in a short nap do not correlate with subsequent encoding performance — related
• Percentage of stage 1 sleep positively correlates with encoding performance in an exploratory analysis — related
• Sleep stage duration and architecture show no significant correlation with memory change in this nap paradigm — reports the opposite
• A short pre-lesson nap improves immediate memory encoding of a biology lesson in high-school students — related