Responsiveness relates to the speed with which the mattress adjusts to your body as you move around on it. A mattress with slow response time is no good for sex: it makes you feel like you are stuck in wet sand. A fast response time makes sure the mattress has returned to its correct position in time. Bounce is different – it helps you. A nice bouncy mattress will rebound as opposed to just absorbing your impact on it. This bounce is what can allow a mattress to be perfect for sex.