Weighted Blanket Load and Sleep Outcomes During Daytime Napping and Overnight Sleep: Two Randomized Crossover Studies

Background/Objectives: Weighted blankets provide deep pressure stimulation and may support relaxation, sleep initiation, and sleep continuity. However, the optimal acute blanket load across different sleep contexts remains unclear. This study examined the acute effects of 7 kg, 9 kg, and 14 kg weighted blankets on daytime napping and overnight home sleep in healthy adults. Methods: Two complementary randomized crossover protocols were integrated into one manuscript. In Protocol A, 20 healthy young adults completed four randomized 30-min laboratory nap conditions: control/sham blanket, 7 kg, 9 kg, and 14 kg weighted blankets. In Protocol B, 20 healthy young adults completed four randomized overnight home sleep conditions: personal blanket control, 7 kg, 9 kg, and 14 kg weighted blankets. All conditions were separated by one-week washout intervals. Portable EEG/EOG polysomnography was used to assess nap and sleep architecture. Relaxation state, handgrip strength, blood pressure, heart rate, and skin/ambient temperature were also assessed where applicable. Results: During daytime napping, no statistically significant differences were observed across conditions for sleep outcomes. During overnight home sleep, the original gender-adjusted repeated-measures model indicated a significant condition effect on sustained sleep efficiency [F(1.929, 9.646) = 14.223, p = 0.001, η²p = 0.740], with higher values under the 9 kg and 14 kg conditions compared with control. However, a sensitivity analysis excluding gender, using the same seven complete cases, did not confirm a significant overall condition effect [F(3, 18) = 0.630, p = 0.605]. Systolic blood pressure decreased after overnight sleep with the 9 kg blanket, while skin and ambient temperatures remained unchanged. Conclusions: Weighted blankets did not significantly affect objective sleep outcomes during the daytime nap protocol. During overnight sleep, the original gender-adjusted model suggested a potential effect on sustained sleep efficiency; however, this finding was based on only seven participants with complete data and was not reproduced in either the sensitivity analysis excluding gender or the non-parametric Friedman analysis. The remaining objective sleep outcomes did not differ significantly across conditions. Accordingly, the sustained sleep efficiency finding should be considered exploratory and model-dependent rather than confirmatory evidence of an effect of weighted blanket load on overnight sleep. Larger and longer-term studies are needed before conclusions regarding the overall effectiveness of weighted blankets for sleep can be drawn.