Motion isolation
Motion isolation is how well a mattress absorbs movement and isolates it so that one person’s movement doesn’t affect other people—and is considered a must-have mattress quality for people with a sleeping partner or young children who crawl into bed at ungodly hours.
Mattresses with fantastic motion isolation transmit absolutely no movement between one half of the bed to the other, allowing you or your partner to toss and turn at will.
Some technologies are better suited to isolating motion than others, and mattress thickness and size also play a role (the thicker and wider, the better).
We provide more colour below.
Why is motion isolation crucial for sleep quality?
Your and your partner’s movement can directly impact sleep quality.
Tossing and turning, getting in and out of bed, and sitting up to sip water can all interrupt the other person’s sleep.
There’s nothing worse than almost nodding off and being woken up because your partner got up to go to the loo. Situations like this are avoidable with the right mattress – all you need is one with sound motion isolation.
Motion isolation describes whether or not movement on one part of your mattress is felt elsewhere on the mattress. For instance, if you toss and turn on one side, does the mattress dip and deform on the other?
There are a few factors at play when a mattress deforms:
- The support system moves in more than one place.
- Vibration transmits through the layers.
- The top comfort layers crumple (usually bunching up)
Manufacturers have their work cut out to solve all three of these factors, although there’s a proven structure that works:
- Pocket springs
- Zoned support
- Absorbent foams
Technologies for optimal motion isolation
Mattresses have layers that contribute to motion isolation.
The absolute worst technology for motion isolation is an open-coiled mattress, which has interconnected springs that compress and move as a single component. No amount of foam or zoned support can prevent open coils from transmitting movement.
The best support system for motion isolation is pocket springs, and the more springs in the mattress, the better to restrict movement.
One thousand pocket springs is a good benchmark, but 1,500, 2,000, or even 3,000 springs are best to provide outstanding motion isolation.
Zoned pocket springs are also handy. These are firmer near sleep zone hot spots, helping to reduce motion transfer and improve comfort levels.
Above this support system should be a thick foam layer. Either:
- Latex foam is the most durable mattress material on the market, with excellent motion isolation and responsiveness. It bounces back instantly, providing a firm but squashy sleep surface ideal for people who frequently switch positions.
- Memory foam – a softer foam that doesn’t bounce back. It compresses right down with your body weight and holds its shape, making it great for pressure relief. It absorbs motion and helps to restrict vibration to the support system.
Mattress size
A larger mattress, such as a king-size, is better for motion isolation because any movement fizzles out over a larger gap.
Upgrading to a king isn’t always possible, but that extra 15cm of width and 10cm of length makes a big difference for motion isolation.
If you have a standard double bed frame with protruding frame and legs right now, you might be surprised that king size divan beds aren’t much broader and longer than standard double bed frames because they are the same width and length as the mattress.
Summing up
Motion isolation matters because it ensures uninterrupted sleep from clumsy partners and young children barrelling into bed.
Pocket spring mattresses are best, and the thicker, the better – look at models over 26cm thick with latex or memory foam top layers.