Biomechanical evaluation of four different mattresses

Effect of a mattress on lumbar spine alignment in supine position in healthy subjects: an MRI study

BACKGROUND

Humans should sleep for about a third of their lifetime and the choice of the mattress is very important from a quality-of-life perspective. Therefore, the primary aim of this study was to assess the changes of lumbar angles, evaluated in a supine position using magnetic resonance imaging (MRI), on a mattress versus a rigid surface.

METHODS

Twenty healthy subjects (10 females, 10 males), aged 32.3 ± 6.5 (mean ± standard deviation), with body mass index 22.4 ± 2.9, completed three evaluations: (i) spine MRI in supine position on a mattress (MAT); (ii) spine MRI in supine position on rigid surface (CON); and (iii) biplanar radiographic imaging in standing position. The following indexes were calculated for both MAT and CON: lumbar lordosis angles L1-L5, L1-S1, L5-S1, and the sacral slope (SS). Further, pelvic incidence (PI) was calculated from the biplanar radiographic images.

RESULTS

Main findings were (i) L1-L5 and SS were greater in MAT than CON (L1:L5: +2.9°; SS: +2.0°); (ii) L5-S1 was lower in MAT than CON (-1.6°); (iii) L1-S1 was greater in MAT than CON only for male subjects (+2.0°); (iv) significant and positive correlations between PI and L1-L5, L1-S1 and SS were observed in both CON and MAT.

CONCLUSIONS

The use of a mattress determined small but statistically significant changes in lumbar angles.

RELEVANCE STATEMENT

The use of a mattress determines small but statistically significant changes in radiological angles describing the sagittal alignment of the lumbar spine when lying in the supine position.

KEY POINTS

• Lordosis angle L1-L5 was greater in MAT than in CON condition (+2.9°). • Sacral slope was greater in MAT than in CON condition (+2.0°). • Lordosis angle L5-S1 was lower in MAT than in CON condition (-1.6°).

The Relationship between Sleeping Position and Sleep Quality: A Flexible Sensor-Based Study

The use of flexible wearable sensors to monitor the impact of sleeping position and turning frequency on sleep and to study sleep patterns can help bedridden patients heal and recover. The flexible wearable sleeping-position monitoring device was designed and developed using a flexible angle sensor and a six-axis motion sensor to measure the dynamic changes in body posture during sleep. Based on the changes in the output parameters of the flexible angle sensor and the six-axis motion sensor, we determined the change in the subject's lying position, verifying and analyzing the relationship between lying position preference, turning frequency, and sleep quality in healthy subjects. The sleeping-position monitoring device was worn by 13 subjects (7 males and 6 females) without sleep disorders before the sleep experiment. They performed more than 50 sleeping-position changes to ensure the accuracy of the monitoring device. Subjects slept in their beds for 8 h per night for 15 nights. During that time, they wore the sleeping-position monitoring device and a wristband sleep-monitoring bracelet on their left hand, and gathered the subjective sleep data using questionnaires. The results show that the most critical influencing factors are sleeping-position preference and frequency of turning. Data analysis reveals that subjects with a preference for right-sided lying and a lower frequency of turning had better sleep quality.

What type of mattress should be chosen to avoid back pain and improve sleep quality? Review of the literature

Energy spent during daily activities is recuperated by humans through sleep, ensuring optimal performance on the following day. Sleep disturbances are common: a meta-analysis on sleep quality showed that 15–30% of adults report sleep disorders, such as sleep onset latency (SOL), insufficient duration of sleep and frequently waking up at night. Low back pain (LBP) has been identified as one of the main causes of poor sleep quality. Literature findings are discordant on the type of mattress that might prevent onset of back pain, resulting in an improved quality of sleep. We conducted a systematic literature review of articles published until 2019, investigating the association of different mattresses with sleep quality and low back pain. Based on examined studies, mattresses were classified according to the European Committee for Standardization (2000) as: soft, medium-firm, extra-firm or mattresses customized for patients affected by supine decubitus. A total of 39 qualified articles have been included in the current systematic review. Results of this systematic review show that a medium-firm mattress promotes comfort, sleep quality and rachis alignment.

Sleeping mattress determinants and evaluation: a biomechanical review and critique

Background

Sleeping mattress parameters significantly influence sleeping comfort and health, as reflected by the extensive investigations of sleeping support biomechanics to prevent sleep-related musculoskeletal problems.

Methodology

Herein, we review the current trends, research methodologies, and determinants of mattress biomechanics research, summarizing evidence published since 2008. In particular, we scrutinize 18 articles dealing with the development of new designs, recommendation criteria, instruments/methods of spine alignment evaluation, and comparative evaluation of different designs.

Results

The review demonstrated that mattress designs have strived for customization, regional features, and real-time active control to adapt to the biomechanical features of different body builds and postures. However, the suggested threshold or target values for desirable spine alignment and body pressure distribution during sleep cannot yet be justified in view of the lack of sufficient evidence.

Conclusions

It is necessary to formulate standard objectives and protocols for carrying out mattress evaluation.

Automatic RBG-depth-pressure anthropometric analysis and individualised sleep solution prescription

INTRODUCTION

Sleep surfaces must adapt to individual somatotypic features to maintain a comfortable, convenient and healthy sleep, preventing diseases and injuries. Individually determining the most adequate rest surface can often be a complex and subjective question.

OBJECTIVES

To design and validate an automatic multimodal somatotype determination model to automatically recommend an individually designed mattress-topper-pillow combination.

METHODS

Design and validation of an automated prescription model for an individualised sleep system is performed through a single-image 2 D-3 D analysis and body pressure distribution, to objectively determine optimal individual sleep surfaces combining five different mattress densities, three different toppers and three cervical pillows.

RESULTS

A final study (n = 151) and re-analysis (n = 117) defined and validated the model, showing high correlations between calculated and real data (>85% in height and body circumferences, 89.9% in weight, 80.4% in body mass index and more than 70% in morphotype categorisation).

CONCLUSIONS

Somatotype determination model can accurately prescribe an individualised sleep solution. This can be useful for healthy people and for health centres that need to adapt sleep surfaces to people with special needs. Next steps will increase model's accuracy and analise, if this prescribed individualised sleep solution can improve sleep quantity and quality; additionally, future studies will adapt the model to mattresses with technological improvements, tailor-made production and will define interfaces for people with special needs.

Effects of Mattress Material on Body Pressure Profiles in Different Sleeping Postures

OBJECTIVES

This study compared the body contact pressure profiles of 2 types of mattresses: latex and polyurethane.

METHODS

Twenty participants were required to lie down on the different mattresses in 3 different postures for 6 minutes, and their body contact pressure profiles were recorded with a pressure mat sensor.

RESULTS

The data indicated that the latex mattress was able to reduce the peak body pressure on the torso and buttocks and achieve a higher proportion of low-pressure regions compared with the polyurethane mattress.

CONCLUSIONS

Latex mattress reduced peak body pressure and achieved a more even distribution of pressure compared with polyurethane mattress across different sleeping postures.

The effect of human-mattress interface's temperature on perceived thermal comfort

In recent years, methods that allow for an objective evaluation of perceived comfort, in terms of postural, physiological, cognitive and environmental comfort, have received a great deal of attention from researchers. This paper focuses on one of the factors that influences physiological comfort perception: the temperature difference between users and the objects with which they interact. The first aim is to create a measuring system that does not affect the perceived comfort during the temperatures' acquisition. The main aim is to evaluate how the temperature at the human-mattress interface can affect the level of perceived comfort. A foam mattress has been used for testing in order to take into account the entire back part of the human body. The temperature at the interface was registered by fourteen 100 Ohm Platinum RTDs (Resistance Temperature Detectors) placed on the mattress under the trunk, the shoulders, the buttocks, the legs, the thighs, the arms and the forearms of the test subject. 29 subjects participated in a comfort test in a humidity controlled environment. The test protocol involved: dress-code, anthropometric-based positioning on mattress, environment temperature measuring and an acclimatization time before the test. At the end of each test, each of the test subject's thermal sensations and the level of comfort perception were evaluated using the ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) scale. The data analyses concerned, in the first instance, correlations between the temperature at the interface and comfort levels of the different parts of the body. Then the same analyses were performed independently of the body parts being considered. The results demonstrated that there was no strong correlation among the studied variables and that the total increase of temperature at interface is associated with a reduction in comfort.

Effect of different mattress designs on promoting sleep quality, pain reduction, and spinal alignment in adults with or without back pain; systematic review of controlled trials

A significant number of US citizens lack appropriate sleep for several reasons. Back pain has been identified as possible cause for inappropriate sleep in adults. Previously, the quality of mattresses and bedding systems has been correlated to the pain perceived by individuals. However, there is controversy in the literature regarding the type and characteristics of a mattress that best serve the purpose of decreasing spinal pain, and improving spinal alignment and quality of sleep. This study gathered the best available evidence in the literature related to this matter through conducting a systematic review of controlled trials that were published since the year of 2000. In those trials, mattresses were subjectively identified as soft, medium firm, firm, or custom inflated. Articles examining the effect of temperature alterations of mattresses on promoting sleep quality and reducing pain were included as well. Twenty-four articles qualified for inclusion into this systematic review. The methodological quality of the reviewed clinical trials was deemed moderate to high according to the PEDro scale. Results of this systematic review show that a mattress that is subjectively identified as a medium-firm mattress and is custom inflated (self-adjusted) is optimal for promoting sleep comfort, quality, and spinal alignment. Evidence is not sufficient yet regarding the appropriate temperature of the optimum mattress; however, warm temperature has been recommended by authors.

Predict human body indentation lying on a spring mattress using a neural network approach

This article presents a method to predict and assess the interaction between a human body and a spring mattress. A three-layer artificial neural network model was developed to simulate and predict an indentation curve of human spine, characterized with the depth of lumbar lordosis and four inclination angles: cervicothoracic, thoracolumbar, lumbosacral and the back-hip (β). By comparing the spinal indentation curves described by the optimal evaluation parameters (depth of lumbar lordosis, cervicothoracic, thoracolumbar and lumbosacral), a better design of five-zone spring mattresses was obtained for individuals to have an effective support to the main part of the body. Using such approach, an operating process was further introduced, in which appropriate stiffness proportions were proposed to design mattress for the normal body types of Chinese young women. Finally, case studies were undertaken, which show that the method developed is feasible and practical.

Effects of interface pressure distribution on human sleep quality

High sleep quality promotes efficient performance in the following day. Sleep quality is influenced by environmental factors, such as temperature, light, sound and smell. Here, we investigated whether differences in the interface pressure distribution on healthy individuals during sleep influenced sleep quality. We defined four types of pressure models by differences in the area distribution and the subjective feelings that occurred when participants slept on the mattresses. One type of model was showed "over-concentrated" distribution of pressure; one was displayed "over-evenly" distributed interface pressure while the other two models were displayed intermediate distribution of pressure. A polysomnography analysis demonstrated an increase in duration and proportion of non-rapid-eye-movement sleep stages 3 and 4, as well as decreased number of micro-arousals, in subjects sleeping on models with pressure intermediately distributed compared to models with over-concentrated or over-even distribution of pressure. Similarly, higher scores of self-reported sleep quality were obtained in subjects sleeping on the two models with intermediate pressure distribution. Thus, pressure distribution, at least to some degree, influences sleep quality and self-reported feelings of sleep-related events, though the underlying mechanisms remain unknown. The regulation of pressure models imposed by external sleep environment may be a new direction for improving sleep quality. Only an appropriate interface pressure distribution is beneficial for improving sleep quality, over-concentrated or -even distribution of pressure do not help for good sleep.

Magnetic resonance imaging zygapophyseal joint space changes (gapping) in low back pain patients following spinal manipulation and side-posture positioning: a randomized controlled mechanisms trial with blinding

OBJECTIVE

The purpose of this study was to quantify lumbar zygapophyseal (Z) joint space separation (gapping) in low back pain (LBP) subjects after spinal manipulative therapy (SMT) or side-posture positioning (SPP).

METHODS

This was a controlled mechanisms trial with randomization and blinding. Acute LBP subjects (N = 112; four n = 28 magnetic resonance imaging [MRI] protocol groups) had 2 MRI appointments (initial enrollment and after 2 weeks of chiropractic treatment, receiving 2 MRI scans of the L4/L5 and L5/S1 Z joints at each MRI appointment. After the first MRI scan of each appointment, subjects were randomized (initial enrollment appointment) or assigned (after 2 weeks of chiropractic treatment appointment) into SPP (nonmanipulation), SMT (manipulation), or control MRI protocol groups. After SPP or SMT, a second MRI was taken. The central anterior-posterior joint space was measured. Difference between most painful side anterior-posterior measurements taken postintervention and preintervention was the Z joint "gapping difference." Gapping differences were compared (analysis of variance) among protocol groups. Secondary measures of pain (visual analog scale, verbal numeric pain rating scale) and function (Bournemouth questionnaire) were assessed.

RESULTS

Gapping differences were significant at the first (adjusted, P = .009; SPP, 0.66 ± 0.48 mm; SMT, 0.23 ± 0.86; control, 0.18 ± 0.71) and second (adjusted, P = .0005; SPP, 0.65 ± 0.92 mm; SMT, 0.89 ± 0.71; control, 0.35 ± 0.32) MRI appointments. Verbal numeric pain rating scale differences were significant at first MRI appointment (P = .04) with SMT showing the greatest improvement. Visual analog scale and Bournemouth questionnaire improved after 2 weeks of care in all groups (both P < .0001).

CONCLUSIONS

Side-posture positioning showed greatest gapping at baseline. After 2 weeks, SMT resulted in greatest gapping. Side-posture positioning appeared to have additive therapeutic benefit to SMT.

Changes in sleep and wake in response to different sleeping surfaces: a pilot study

Six married couples (12 adults, mean age 34.8 years) were randomized as couples in a cross-over design to sleep on a queen-size conventional mattress for 2 weeks and a specially-designed pressure-relief mattress for 2 weeks. The pressure-relief mattress was designed to reduce the number of contact points exceeding 30 mm Hg. Actigraphic measurements of sleep and self-reports of sleep and daytime symptoms were collected at baseline for 2 weeks on each couple's home mattress and box springs at home, followed by 2 weeks of data collection on each randomized mattress for a total of 6 weeks of data collection. Pressure maps were created for each participant on each sleeping surface. There were no significant differences between the randomized sleeping surfaces for any measure of actigraphic sleep or self-reported sleep and daytime symptoms. However, poor pressure relief performance of the home mattress was associated with better actigraphic sleep on the randomized pressure-relief mattress. We conclude that while pressure-relief mattresses may not be universally preferred, baseline characteristics of the sleeper and/or their mattress may explain performance and sleeper preferences on future mattress selection.

Spine alignment in men during lateral sleep position: experimental study and modeling

BACKGROUND

A proper sleep system can affect the spine support in neutral position. Most of the previous studies in scientific literature have focused on the effects of customary mattresses on the spinal alignment. To keep the spine in optimal alignment, one can use sleep surfaces with different zonal elasticity, the so called custom-made arrangements. The required stiffness of a sleep surface for each individual can be obtained by changing this arrangement applying the experimental method and modeling.

METHODS

In experimental part, the coordinate positions of the markers mounted on the spinous processes of the vertebrae of 25 male volunteers were registered in frontal plane through the optical tracking method and so the spinal alignment was obtained in lateral sleep position on soft and firm surfaces and on the best custom-made arrangement. Thereupon the π-P₈ angles were extracted from these alignments and then were compared with each other. In modeling part the anthropometric data of four different types of volunteers were used. And then the models built in BRG.LifeMOD (ver. 2007, Biomechanics Research Group, Inc., USA) based on these data and in accordance with the experimental tests, were analyzed.

RESULTS

The one way ANOVA statistical model and the post hoc tests showed a significant difference in the π-P₈ angles between soft & custom-made and soft & firm mattresses at the p = 0.001 level and between firm & soft mattresses at the p = 0.05 level. In modeling part, the required stiffness of the sleep surface for four weight-dimensional groups was acquired quantitatively.

CONCLUSIONS

The mattress with a custom-made arrangement is a more appropriate choice for heavier men with pronounced body contour. After data fitting, it was observed that the variations of spinal alignment obtained from both methods have the same trend. Observing the amount of required stiffness obtained for the sleep surface, can have a significant effect on keeping the spine healthy.

Your Pillow May Not Guarantee a Good Night's Sleep or Symptom-Free Waking

PURPOSE

To describe the performance of the pillow that participants usually slept on with respect to retiring and waking cervico-thoracic symptoms, pillow comfort, and sleep quality.

METHODS

Participants (n=106) were systematically recruited for a field trial comparing their own pillow and five trial pillows. Participants provided daily retiring and waking symptom reports and sleep-quality and pillow-comfort ratings prospectively for 1 week on each pillow. Linear and logistic regression models were used to investigate the relationship between pillow use, age, gender, sleep quality, pillow comfort, and waking and temporal (overnight) symptom reports.

RESULTS

No waking symptoms were reported by 42.5% of participants on their own pillow. Regular waking symptoms, failure to relieve retiring symptoms, uncomfortable pillows, and/or poor-quality sleep were reported by over 50% of participants. All participants who reported poor sleep quality also reported poor pillow comfort. Pillow-comfort reports were not related to any waking symptom report; however, reports of poor sleep quality were significantly related to waking cervical stiffness (adjusted odds ratio [AOR]=4.3 [Confidence Interval (CI): 1.3-15.6]) and scapula pain (AOR=6.1 [CI: 1.1-31.6]). Feather pillow users provided consistently low reports of pillow comfort and sleep quality.

CONCLUSION

Many participants appear to have made poor pillow choices, as poor sleep quality, low pillow comfort, and waking symptoms were common. Further research is required to understand why people choose particular pillows to sleep on, as well as to identify the best fit between person and pillow to optimize sleep quality and reduce waking symptoms.

Ergonomics in bed design: the effect of spinal alignment on sleep parameters

This study combines concepts of bed design and sleep registrations to investigate how quality of spine support affects the manifestation of sleep in healthy subjects. Altogether, 17 normal sleepers (nine males, eight females; age 24.3±7.1 years) participated in an anthropometric screening, prior to the actual sleep experiments, during which personalised sleep system settings were determined according to individual body measures. Sleep systems (i.e. mattress and supporting structure) with an adjustable stiffness distribution were used. Subjects spent three nights of 8 h in bed in the sleep laboratory in a counterbalanced order (adaptation, personalised support and sagging support). During these nights, polysomnography was performed. Subjective sleep data were gathered by means of questionnaires. Results show that individual posture preferences are a determinant factor in the extent that subjects experience a negative effect while sleeping on a sagging sleep system. STATEMENT OF RELEVANCE: This study investigated how spine support affects sleep in healthy subjects, finding that the relationship between bedding and sleep quality is affected by individual anthropometry and sleep posture. In particular, results indicate that a sagging sleep system negatively affects sleep quality for people sleeping in a prone or lateral posture.

Effects of Using a High-Density Foam Pad Versus a Viscoelastic Polymer Pad on the Incidence of Pressure Ulcer Development During Spinal Surgery

The purpose of this study was to evaluate the effect of high-density foam (HDF) pads versus viscoelastic polymer (VP) pads in the prevention of pressure ulcer formation during spinal surgery and their cost-effectiveness. Subjects were 30 patients who underwent spinal surgery for more than 3 hr in a prone position. One side of the chest and iliac crest was padded with HDF pads and the other side was padded with VP pads. An Xsensor® pressure measuring sheet was placed between the pad and the patient. Bilateral chest and iliac crest points were observed for the presence of pressure ulcers at 30 min after the operation. Results showed that a pressure ulcer had occurred at 9 of 120 compression points (7.5% of the total), 30 min after the operation. Risk evaluation showed that female gender, weight <50 kg, and body mass index (BMI) <18 kg/m2 as well as location (the iliac crest) were all risk factors for development of pressure ulcers. The most significant factor was BMI <18 kg/m2. The average and peak pressures measured at the points padded with the VP pads were significantly lower than those padded with the HDF pads. However, there was no significant difference between the VP and the HDF pads regarding ulcer prevention. Because the cost of a VP pad is 250 times greater than that of an HDF pad of similar size, the VP pad should only be considered for use in high-risk patients.

Usage of high-performance mattresses for transport of Indo-Pacific bottlenose dolphin

Ground transport can be a stressful operation for dolphins if the long period of restraint causes damage to internal organs, especially to the lung, generated by their own weight. Buoyancy is deprived from dolphins under moist transport, in which dolphins are transported on mattresses. Upgrading mattresses is an effective way to modify the transportation method so as to compensate for the loss of buoyancy. In Indo-Pacific bottlenose dolphins (Tursiops aduncus), we tried to find mattresses that performed well at distributing the dolphins' weight and preserved their pulmonary function. When using EV-17 (thickness, 50 mm) put on EE-20 (thickness, 50 mm), a wider support area, less extreme changes in pressure, and lower maximum pressures were observed compared with other mattress systems tested. On this mattress system, lower breathing rates, lower heart rates, and higher exhaled CO(2) concentrations were shown compared with using standard mattresses. These results suggest that the performance of the combination of EV-17 and EE-20 is better than that of the standard mattress in terms of the cardiopulmonary function of dolphins. Zoo Biol 27:331-340, 2008. (c) 2008 Wiley-Liss, Inc.

Effects of surface characteristics on the plantar shape of feet and subjects' perceived sensations

Orthotics and other types of shoe inserts are primarily designed to reduce injury and improve comfort. The interaction between the plantar surface of the foot and the load-bearing surface contributes to foot and surface deformations and hence to perceived comfort, discomfort or pain. The plantar shapes of 16 participants' feet were captured when standing on three support surfaces that had different cushioning properties in the mid-foot region. Foot shape deformations were quantified using 3D laser scans. A questionnaire was used to evaluate the participant's perceptions of perceived shape and perceived feeling. The results showed that the structure in the mid-foot could change shape, independent of the rear-foot and forefoot regions. Participants were capable of identifying the shape changes with distinct preferences towards certain shapes. The cushioning properties of the mid-foot materials also have a direct influence on perceived feelings. This research has strong implications for the design and material selection of orthotics, insoles and footwear.

Study of skin-fabric interactions of relevance to decubitus: friction and contact-pressure measurements

BACKGROUND/PURPOSE

Prolonged pressure as well as friction and shear forces at the skin-textile interface are decisive physical parameters in the development of decubitus. The present article describes the contact phenomena at the skin-textile interface and the development of a purpose-built textile friction analyser (TFA) for the tribological assessment of skin-fabric interactions, in connection with decubitus prevention.

METHODS

Interface pressure distributions were recorded in the pelvic and femoral regions between supine persons and a foam mattress. Fabrics made of various natural and synthetic yarns were investigated using the TFA. A vertical load of 7.7 kPa was applied to the swatches, simulating high interface pressures at the skin-fabric interface and clinical conditions of bedridden persons. Fabrics were rubbed in reciprocating motions against a validated skin-simulating material to determine static as well as dynamic friction coefficients (COFs).

RESULTS

Maximum contact pressures ranged from 5.2 to 7.7 kPa (39-58 mmHg) and exceeded the capillary closure pressure (32 mmHg) in all investigated bedding positions. For both COFs, a factor of 2.5 was found between the samples with the lowest and highest values. Our results were in a similar range to COFs found in measurements on human skin in vivo. The results showed that our test method can detect differences of 0.01 in friction coefficients.

CONCLUSION

TFA measurements allow the objective and reliable study of the tribology of the skin-textile biointerface and will be used to develop medical textiles with improved performance and greater efficacy for decubitus prevention.

Effects of bedding systems selected by manual muscle testing on sleep and sleep-related respiratory disturbances

In this study, we investigated the feasibility of applying manual muscle testing (MMT) for bedding selection and examined the bedding effect on sleep. Four lay testers with limited training in MMT performed muscle tests for the selection of the bedding systems from five different mattresses and eight different pillows for 14 participants with mild sleep-related respiratory disturbances. For each participant individually, two bedding systems-one inducing stronger muscle forces and the other inducing weaker forces-were selected. The tester-participant pairs showed 85% and 100% agreement, respectively, for the selection of mattresses and pillows that induced the strongest muscle forces. The firmness of the mattress and the height of the pillow were significantly correlated with the body weight and body mass index of the participants for the selected strong bedding system but not for the weak bedding system. Finally, differences were observed between the strong and the weak bedding systems with regard to sleep-related respiratory disturbances and the percentage of slow-wave sleep. It was concluded that MMT can be performed by inexperienced testers for the selection of bedding systems.

Objective firmness, average pressure and subjective perception in mattresses for the elderly

For elderly people, the desirable situation of living independently means facing everyday tasks and risks alone [Monk et al., 2006. Towards a practical framework for managing the risks of selecting technology to support independent living. Appl. Ergon. 37, 599-606]. One such task is buying a mattress through the same channels as younger people. Quite short trials (if any) in the store are usually the only basis for choice. Despite the long-term effects a mattress may have on the user, acceptance or rejection largely depends on this extremely short trial experience. This paper aims to cover the salient mechanical aspects of comfort and usability (rolling, getting up). The results should help manufacturers to know if the long-term benefits of their products are perceived in the short term by senior citizen customers. Four mattresses for the elderly chosen from a sample of 17 available on the Spanish market were compared in pairs for short-term effects (1 min pressure with both hands, 1 min sitting, 1 min lying on back, and 1 min lying on side), simulating a store purchasing trial by a group of young and elderly people in terms of differences between perceived firmness, usability (ease of movement) and comfort. The results of these comparisons were correlated to differences in objective properties such as pressure distribution and objective firmness. No differences in perception were found between young and old users. Only two of the four test methods for perceiving mattress firmness were necessary to explain the majority of variance: pressing the surface of the mattress with a part of the body (both hands or buttocks), and contact using the entire body (lying on back or side). A number of significant relationships were found, with the following of note: increments in 'objective firmness' (estimated from test load/deflection) correlate positively to increments in 'perceived firmness'; increments in 'average pressure' (measured using a mannequin) correlate positively to increments (within certain limits) in 'perceived firmness'; increments in 'objective firmness' and in 'average pressure' are associated with increments in 'overall comfort' and with reductions in 'difficulty in rolling". Finally, it was found that people with a higher body mass index tend to be (weak correlation) more sensitive to changes in 'objective firmness'.