From: Importance of the Right Sleep System at Dormia Direct (classicmattress.com)
This company is selling memory foam mattresses so the following is probably pseudo-science.

A truly restful night's sleep rejuvenates your entire body. The more your sleep is disturbed, the more your heart is unnecessarily taxed. A conventional bed's harder surface causes you to toss and turn more keeping your heart beating harder than it should. Too much mattress pressure on shoulders and hips also affects circulation causing your heart to beat harder to keep blood flowing. Synthetic foams found in most U.S. mattress reflect body heat and humidity making the heart work harder to compensate.

The right mattress creates the kind of environment that promotes the deep sleep that gives your heart a rest by providing better support even weight and pressure distribution which allows better circulation and minimizes tossing and turning. These sleep systems absorb excess body heat and humidity better than conventional synthetic mattresses.

Your sleep comes in 2 phases: REM (Rapid Eye Movement) and non-REM. Non-REM sleep is the quiet sleep that does the most good for your body: your cells replenish, your spine reabsorbs water to stay flexible, muscles fully relax, skin re-hydrates and heals and circulation is steady.

Conventional synthetic beds or mattresses with a hard surface provide improper support and reflect heat and moisture this disturbs non-REM sleep and forces you into REM sleep. During REM sleep, your heart rate and blood pressure increase, breathing is shallow and your brain waves increase resulting in very little rest. Studies have shown that proper posture and support promote non-REM sleep. The right sleep system fosters all the principles that lead to this deep, healthy sleep.

The hot topic in sleep research is the effect of temperature and humidity on the body and the quality of sleep. Thermal imbalance is probably the single greatest detriment to sleep. Synthetic bedding and mattresses trap and hold moisture causing higher humidity. The heart rate increases; by as many as ten more beats a minute. Blood pressure climbs, sleep becomes shallow, so there is less non-REM. These synthetics provide a perfect climate for molds, mildew and dust mites to thrive. The right sleep system will absorb body heat and conducts moisture away from the body.

The more we read about U.S. mattresses, the clearer it becomes they're just not healthy for us. A standard flat mattress puts higher pressure on shoulders, hips and thighs, which constricts the veins and disrupts cell structure. Heart rate increases as the heart pumps harder to keep blood flowing causing blood pressure to climb stressing your body. Major studies show that pressure becomes unhealthy at levels over 40 mmHg (millimeters of mercury). Standard US mattresses put an average of 56 mmHg on weight bearing surface of the body. When lying on your side, you can be receiving 61 mmHg of pressure on the hip alone. This causes people to toss and turn up to 200 times a night as opposed to 12 to 40. The more restless you are, the less rest your body gets.

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Mattresses

last updated 16 Dec 2002