Motion Isolation

Motion isolation measures how much energy travels through the mattress when one partner moves, gets in or out of bed, or shifts position. Higher isolation = less movement transferred to your sleeping partner = less sleep disruption.

Memory foam is the gold standard for motion isolation — the slow-recovering viscoelastic structure absorbs nearly all kinetic energy locally rather than transmitting it across the surface. Pocketed coils are the second-best option, with each coil compressing independently.

Traditional Bonnell or continuous-coil innerspring construction has the worst motion isolation by a wide margin — the interconnected coil grid transmits movement across the entire mattress surface, often causing the 'partner gets in bed and the whole mattress jiggles' problem.

Lab measurements use a 10 lb steel ball drop from 12" away, measuring peak G-force at a sensor on the opposite side of the mattress. Excellent isolation: under 0.05 g. Good isolation: 0.05–0.10 g. Acceptable: 0.10–0.15 g. Noticeable: above 0.15 g.

Motion isolation describes how well a mattress absorbs movement instead of transmitting it. We test it by dropping a weight at a fixed distance from a sensor and measuring propagation, which separates the marketing claim from the physics: memory foam absorbs almost everything, latex and connected innersprings transmit noticeably more.

It only matters if you share the bed, and it trades directly against ease of movement. The beds that best isolate a restless partner are also the beds that feel hardest to roll over on. Couples with different sleep schedules should prioritize it; solo sleepers can trade it for responsiveness.