Most people have slept at least part of their life on a traditional innerspring mattress and are familiar with the bouncy feel these beds have. Springs help a bed contour to your body and "spring" back to create that bouncy feel when you sit or lie down. Because of the way springs are constructed, movement can be felt across the whole surface of the bed, allowing people to feel every move their partner makes. As a result, motion transfer is a common cause of sleep disturbance with innerspring beds. When one partner moves around or gets in and out of bed at night, they often wake the other partner from sleep.
Because sleep deprivation can lead to serious health problems, and in fact is an epidemic problem in the modern world, alleviating sleep disturbance caused by a restless bedmate can significantly improve your quality of life. Some pocket coil spring mattresses have less motion transfer compared to traditional spring beds. But the real winner for controlling motion transfer and the resulting sleep disturbance between partners is the memory foam mattress.
Memory foam was originally created by NASA to reduce pressure on astronauts during lift off. But another purpose the original engineers had in mind for memory foam was to reduce vibration (motions transfer). Likewise, memory foam was originally incorporated into mattresses to reduce pressure on body joints, but also has the secondary benefit of preventing motion transfer between sleeping partners.
Memory foam inhibits motion transfer because it recovers slowly from impressions. When you press your hand into memory foam and then take it away, memory foam does not bounce right back. Instead it slowly recovers its shape. The same thing applies when you lie down on a memory foam bed. You push against the bed, but it does not push back against you with equal force or speed.
An innerspring bed reacts to pressure much the same way a trampoline does. When you jump down on a trampoline it will force you back with equal speed and pressure - making you fly into the air. If you were to jump on an innerspring mattress, you get the same effect, which is why children love to jump on them. But a memory foam mattress's reaction is as slow as a turtle. It will push back when you push on it, but only slowly.
Because most innerspring beds have connecting coils, a bump on one side of the bed will cause motion across the surface of the entire bed. But an all foam bed limits motion to the immediate area that you are pushing against. For example, just sitting on the edge of a spring mattress can be felt by someone lying on the other side of the bed. But on a memory foam bed, you can not feel a person sitting on the other side of the bed because the motion is limited; it simply does not reach you.
A popular commercial today features a memory foam mattress with a glass of red wine in one corner of the bed and a woman jumping on an opposite corner of the bed. Try as she may, her jumping just won't spill the glass of wine. Then the woman tries the same thing on an innerspring bed and the wine spills all over. The demonstration shows a stark contrast in motion transfer between innerspring and memory foam mattresses.
Memory foam mattresses have reduced the motion transfer between partners to almost zero, allowing people to get in and out of bed without waking each other up. For couples experiencing sleep deprivation due to motion transfer, a memory foam mattress can make a dramatic improvement in their quality of sleep. Besides all the other health benefits to be gained from reducing pressure points, memory foam beds have become the best solution for people looking for long periods of stillness that promote deeply restful sleep.