The Effect of Mattress Firmness on Sleep Architecture and PSG Characteristics.

Background: The influence of sleep environments on sleep quality is well-established; however, the specific role of mattress design remains underexplored. Existing studies focus primarily on ergonomic aspects, such as pressure relief and spinal support, yet lack conclusive evidence linking these features to improved sleep quality.

Objective and methods: This study aimed to evaluate the effects of mattress firmness on sleep quality. Twelve participants with a moderate body mass index (BMI) were tested across three levels of mattress firmness: soft (32.6 HA), medium (64.6 HA), and firm (83.8 HA). Sleep architecture and neurophysiological activity were assessed using polysomnography (PSG), with EEG-derived features, including power spectral characteristics, sleep spindle activity, and slow-wave parameters, further analyzed.

Results: Our findings indicate that a medium-firm mattress provides better sleep quality, reflected in a narrower range (Range=xmax-xmin) of sleep duration, efficiency, and sleep latency, as well as increased sleep spindle activity. A repeated-measures ANOVA revealed a significant effect of mattress type on sleep latency (p < 0.05, partial η²=0.26), with sleep latency being longer on the soft mattress (12.42 ± 1.94 min) than the medium mattress (7.71 ± 1.31 min, p < 0.05). Another repeated-measures ANOVA showed significant differences in stage transitions (p < 0.05, partial η²=0.32), with more transitions on the soft mattress (29.17 ± 2.35) compared to the firm mattress (21.75 ± 2.13, p < 0.05). The firm mattress yielded mixed results, suggesting suitability for some individuals but not universally. Post-sleep vigilance differences were not statistically significant.

Conclusion: This study provides evidence that mattress firmness significantly influences sleep quality, with medium firmness offering optimal outcomes for individuals with a moderate BMI. The findings contribute to the development of scientifically informed mattress designs, including smart mattresses aimed at improving sleep quality.