Sleep disorders affect 40% of the adult population each year and are often associated with morbidity and mortality (Kripke et al., 2002; F.-Z. Low et al., 2017). Sleep quality plays a vital role in the overall quality of our lives. Therefore, a good sleep helps to create a quality life rhythm. A quality sleep reduces fatigue and increases physical regeneration (Khaleghipour et al., 2015). Poor sleep quality is due to various environmental factors such as temperature, light, noise and bed quality (Lei et al., 2009). It has been reported that 7% of sleep problems are caused by inappropriate mattresses that affect the load on the spine during sleep (F. Z. Low et al., 2017). Body contact pressure is a measure of the distribution of body weight across the body surface in contact with the mattress. A well-designed mattress usually has the ability to minimize high pressure points applied to the body. However, if the bed is not suitable for the person, pressure sores may develop in the body parts where pressure is intense (Cullum et al., 2004). The areas most affected by high pressure are usually the hips, shoulders and back, which can affect sleep quality and result in drowsiness or body stiffness throughout the day (Jacobson et al., 2002). A recent study by Bae and Ko compared the bed positions of hospital beds and found that a head-to-foot angle of 30° is the best position to reduce the likelihood of decubitus ulcers occurring in patients in high-pressure risk areas (Bae & Ko, 2013). In the light of previous studies, it has been observed that there is no study comparing many bed types designed using different materials for individual-specific postures. Biomechanical comparison of these bedding materials in individuals with different posture types and sleeping in different sleeping positions will allow us to provide new insights into their pressure distribution abilities. The aim of this study is to measure the effect of mattresses made of different mattress materials on body contact pressure profiles in individuals with different postures in various sleeping positions. It will be evaluated using maximum body pressure and pressure distribution as outcome measures.

Inclusion Criteria:

• Volunteer to participate in research

Exclusion Criteria:

• Having a history of back, shoulder or neck pain in the last 6 weeks
• Having a surgical operation in the last 8 weeks

210 participants (105 women, 105 men) between the ages of 18-85 with 7 different posture types (Normal posture, Lordotic posture, "sway back" posture, straight waist posture, head forward posture, scoliotic posture and kyphotic posture) will be included in this study. .