P115 Towards the Perfect Mattress: influence of age on soft tissue pressure

Abstract Introduction Little is known about the relationship between mattress mechanics and sleep comfort in healthy people. Excessively firm mattresses increase arousal frequency, suggesting that control of soft tissue pressures and spinal distortion plays a role in improving sleep quality. Methods This study presents findings from a parametric finite element (FE) analysis to investigate influence of age, anthropometry, mattress stiffness and mattress technology on soft tissue pressure in the pelvis area during supine lying. A subject-specific multi-geometry 3D FE model was developed from a healthy 19-year-old male providing the basis for the parameterization of body size and age (20, 50 and 80 years old) by estimating increase in intramuscular adipose tissue (IMAT) to reflect stiffening of muscle tissue. Mattress stiffness (soft and firm) and technology (foam and spring) were also tested. Non-linear mechanical behaviour of foam was derived from compression testing, and comparable spring mattress properties were derived as linear elastic. FEM predicted soft tissue pressures and mattress deformation were analysed for relationship with age, anthropometry, mattress firmness and mattress technology via linear regression modelling. Results Soft tissue pressure increased with age (β = 0.1 kPa/year, p = 0.0047). In comparison to springs, foams were effective at reducing soft tissue pressure, with the magnitude of this effect increasing with age (age 20: -22.4%, age 50: -33.4%, age 80: -35.7%). Conclusions Increased soft tissue pressure may contribute to elevated awakening and arousal frequencies in older populations. Further research should investigate influence of customised non-linear mattress characteristics on overall sleep quality.