We all know that sleep after leg surgery sucks, and most limb lengthening patients suffer from sleep deprivation. I was among them, getting at most 3 hours of actual sleep out of spending 12 hours in bed. That, along with the lack of weight bearing, contributed to intense apathy and frequent depressive episodes.
About a month after my femurs surgery, it occurred to me that the reason we femur patients couldn't sleep much was that the body naturally shifts positions during the night to avoid pressure sores, but due to the hip screws, it's painful to sleep in any other position than on your back. When you turn to the side, you automatically wake up (or if you're dead asleep due to using Ambien or such, you wake up in the morning with terrible hip pain).
So it makes sense that a very soft and BOUNCY mattress would cradle the body better, reducing the need to turn, and softening the pressure on the screws if you did turn. The best of such mattresses are made of latex foam and can be quite expensive. However, there's a cheap alternative - a twin-size latex foam mattress topper. I bought this 3" one for $150 and... IT DAMN WORKED. I went from 2-3 hours a night to 5-6, and able to nap easily for an hour or two after morning PT sessions. I recommend getting the thickest you can find. The only disadvantage is that it's harder to move in it than on a firm bed, but that's not the point of beds... get out and do PT. Or move to the other half of the bed (for non-Americans, "twin" size is about 1m wide and as long as the bed).
That was about 4 weeks after the femurs surgery. Now, ~7 weeks later, I get 6 hours typically, to 8 hours on the weekends when there's no PT to wake up for. Plus naps, I would say that I'm less and less tired than I used to be, and I'm slowly regaining my full mental capacity.
Along with a portable urinal to not have to go to the bathroom 6 times a day, these were the two most useful tools I've used in my LL journey.