A split sheet for an adjustable bed
Short answer: A split sheet has an opening in the middle so the mattress can bend without the sheet tightening. Without that opening the sheet pulls together every time the bed is raised, and it ends up popping off the corners.
What an adjustable bed does
An adjustable bed can raise the head or the foot end, so the mattress bends in the middle. It is used for sitting up in bed, reading or resting with the legs raised. The bed changes shape, which puts different demands on the sheet than a flat bed does. See bamboo bedding.
Why an ordinary sheet does not work
When the head end is raised, the distance across the mattress gets shorter on top and longer underneath. A sheet without a split cannot follow that movement. It is pulled to one side, loses its grip and pops off the corners. That happens often, and it is annoying to straighten every morning.
How a split sheet is built
There is an opening or split running across, typically with elastic at each end. The two halves can move independently, so the mattress can bend without the sheet tightening. The elastic holds each half in place around its part of the mattress. See bamboo split sheets.
The two halves
Each half of the sheet fits around its part of the mattress. When the bed moves, the two parts follow their own movement and do not pull on each other. That property keeps the sheet lying smooth, even when the bed stays in a tilted position all evening. It makes the bed nicer to use.
Where the split sits
The split typically sits at the transition between back and seat, roughly a third of the way down. That is where the mattress bends, so that is where the opening must lie. Check that the position suits your bed's bending point before ordering, because a split in the wrong place is no use.
How to choose the size
Measure the mattress length, width and height as for an ordinary sheet. The height decides how deep the edge must be, so the sheet stays on. Also check that the split position suits the bed's bending point. If you hesitate between two sizes, take the one with the deeper edge. See bamboo sheets.
The bending point
The bending point depends on the model. Some beds bend closer to the head end than others, and some have several bending points. Look in the bed's manual or measure yourself where the mattress bends when you raise the head. Write the measurement down and compare it with the sheet's stated split position before you decide.
Two ordinary sheets
Some think of using two ordinary sheets instead of one split sheet. That works on a divided bed, but not on a single mattress. If the mattress lies in one piece, a sheet over each half will not follow the movement and will slide off. A split sheet is built for exactly that task.
Price and care
A split sheet is often a little more expensive than an ordinary one, because there is more sewing in it. Wash it as the label says, and do not overfill the machine, so the elastic is not overstretched. A sheet that fits and is cared for properly lasts longer and stays on better.
Frequently asked questions
Can you use two ordinary sheets instead?
That works on a divided bed, but not on a single mattress. If the mattress lies in one piece, two sheets do not follow the movement and slide off.
Where does the split typically sit?
At the transition between back and seat, roughly a third of the way down. Always check your bed's bending point before ordering, though.
Are they more expensive?
Often a little, because there is more sewing in them. In return they are built for a bed that bends and stay on better.
