Bed mobility & sleep comfort glossary

Plain-language definitions for 37 terms used across our guides. Each term is explained in the context of home comfort and bed mobility, not as medical advice.

A

Adhesive capsulitis: The clinical name for frozen shoulder. The shoulder joint capsule thickens and tightens, making overhead and rotational movements painful. In bed, this can make it difficult to reposition your arm when turning or to push yourself upright in the morning.; See also: Frozen shoulder, Range of motion
Ankylosing spondylitis: A condition where the spine gradually stiffens and may partially fuse. People with AS often cannot curl or twist through their trunk, so every bed turn becomes a rigid, full-body rotation requiring more effort and more friction against the sheet.; See also: Log-roll turn, Bed friction

B

Bed edge anxiety: The fear of rolling off the edge of the bed during a turn, especially common for people who live alone or have reduced body awareness at night. This anxiety can cause people to stop turning entirely, leading to stiffness and pressure discomfort.; See also: Night repositioning, Bed mobility
Bed friction: The resistance between your body (or clothing) and the bed surface when you try to slide or turn. High bed friction means more effort to reposition. It is influenced by sheet material, clothing texture, mattress type, and body weight distribution.; See also: Coefficient of friction, Mattress friction zone, Friction seal
Bed mobility: The ability to move around in bed independently — turning onto your side, adjusting position, scooting toward the edge, and getting in and out. Bed mobility is a key part of sleep comfort and can be affected by pain, stiffness, fatigue, or high-friction surfaces.; See also: Night repositioning, Pre-standing sequence

C

Coefficient of friction: A measurement of how much two surfaces resist sliding against each other. In bed mobility, a lower coefficient of friction between you and the sheet means less effort to reposition. Cotton-on-cotton is relatively high friction; satin-on-satin is very low.; See also: Bed friction, Slide sheet
CPAP compliance during repositioning: Maintaining a proper mask seal and hose position while turning in bed with a CPAP machine. Repositioning can pull the mask off-centre or tangle the hose, breaking the air seal and waking the user. Techniques like turning head-last and routing the hose over the pillow can help.; See also: Night repositioning, Two-part turn

E

Energy budgeting: A self-management strategy used by people with ME/CFS and similar fatigue conditions. Every physical activity, including turning in bed, costs energy from a limited daily budget. Reducing the effort of each bed turn helps preserve energy for other activities.; See also: Post-exertional malaise, Bed mobility

F

Fabric grab: When bedding fabric catches on skin or clothing during a turn, creating sudden resistance. Common with flannel sheets, jersey cotton, and textured pyjamas. Fabric grab can stall a turn mid-way, leaving you twisted at an uncomfortable angle.; See also: Friction seal, Bed friction, Mattress friction zone
Friction seal: The grip that forms when fabric presses against skin or clothing under body weight. The heavier the contact and the rougher the surfaces, the stronger the seal. Breaking a friction seal requires either lifting (which takes effort) or sliding on a low-friction layer.; See also: Bed friction, Fabric grab, Slide sheet
Frozen shoulder: A condition where the shoulder joint becomes painfully stiff, restricting movement. In bed, frozen shoulder makes it hard to lie on the affected side, to reach across your body during a turn, or to push yourself up from a side-lying position.; See also: Adhesive capsulitis, Range of motion

H

Hemiplegia: Weakness or paralysis affecting one side of the body, often following a stroke. In bed, the weaker side cannot contribute to turning, so all movement must be initiated by the stronger side. Turning toward the weak side can feel like falling; turning away from it requires dragging it along.; See also: Bed mobility, Lateral repositioning
Hip precautions: Movement restrictions given after hip replacement surgery, typically limiting how far you can bend, cross your legs, or rotate the hip. In bed, hip precautions affect which turning techniques are safe and usually require keeping a pillow between the knees during repositioning.; See also: Log-roll turn, Segmented turn
Hypermobility spectrum: A range of conditions where joints move beyond the typical range, including hypermobility spectrum disorder (HSD) and Ehlers-Danlos syndrome (EDS). During sleep, uncontrolled turns can cause joints to sublux or overextend, so controlled, staged turning techniques are important.; See also: Subluxation, Joint stabilisation, Two-part turn

J

Joint stabilisation: Keeping a joint in a safe, supported position during movement. In bed mobility, this means controlling each phase of a turn so that shoulders, hips, and knees stay aligned rather than flopping into an unsupported position that could strain ligaments or cause subluxation.; See also: Hypermobility spectrum, Subluxation, Segmented turn

L

Lateral repositioning: Moving sideways across the mattress rather than rolling or twisting. This technique lets you shift your hips to a fresh patch of mattress before turning, which is especially useful for escaping a memory foam dip or moving away from the bed edge.; See also: Memory foam dip, Slide sheet, Bed edge anxiety
Log-roll turn: A turning technique where the whole body rotates as a single unit, like a log, with no twist between hips and shoulders. Used when spinal rotation needs to be avoided, such as after back surgery, with ankylosing spondylitis, or during pregnancy with pelvic girdle pain.; See also: Segmented turn, Hip precautions, Ankylosing spondylitis

M

Mattress friction zone: The area of the mattress surface directly under your heaviest body parts (typically hips and shoulders) where friction is greatest. This is where a body impression or dip forms over time, and where the most effort is needed to initiate a slide or turn.; See also: Bed friction, Memory foam dip, Friction seal
Memory foam dip: The body-shaped valley that forms in a memory foam mattress as it conforms to your weight and heat. The dip cradles you in place, making it harder to turn because you must first climb out of the depression. Lateral sliding onto a flat patch of mattress is often easier than trying to roll out of the dip directly.; See also: Lateral repositioning, Mattress friction zone, Bed friction
Momentum-assisted turn: A repositioning technique that uses a gentle rocking motion to build enough momentum to complete a turn with less peak effort. Instead of one big push, you rock your knees or hips two or three times, then use the final swing to carry you over. Helpful when strength is limited.; See also: Two-part turn, Segmented turn, Energy budgeting

N

Night repositioning: Any change of position during sleep, whether conscious or unconscious. Most people reposition 10-20 times per night. When pain, stiffness, or fatigue makes repositioning difficult, sleep quality drops because the body cannot relieve pressure or restore circulation naturally.; See also: Bed mobility, Pressure redistribution

P

Pelvic girdle pain: Pain around the pelvis, often at the pubic bone or sacroiliac joints, common during pregnancy and postpartum. Turning in bed can feel like the pelvis is separating. Keeping the knees together (with a pillow between them) and turning hips-and-knees as a locked unit helps reduce this pain.; See also: Log-roll turn, Hip precautions
Plantar fasciitis: Inflammation of the tissue along the sole of the foot, causing sharp heel pain especially with the first steps of the day. In the bed mobility context, how you position your feet before standing and the surface you step onto matter. Dangling feet off the bed edge and flexing gently before standing can reduce that first-step jolt.; See also: Pre-standing sequence, Range of motion
Post-exertional malaise: A worsening of symptoms after physical or mental effort, characteristic of ME/CFS. Even turning in bed can trigger PEM if the effort is high enough. Reducing the physical cost of each repositioning by lowering friction and using micro-movements helps keep bed turns below the threshold that triggers a crash.; See also: Energy budgeting, Bed mobility
Pre-standing sequence: A series of small steps that prepare your body to move from lying to standing: roll to side, scoot to edge, lower legs off, push up with the forearm, sit briefly, then stand. Breaking the transition into stages reduces the peak effort and dizziness that can come from getting up in one movement.; See also: Bed mobility, Bed edge anxiety
Pressure redistribution: Spreading body weight over a larger area or shifting it to a different area to prevent prolonged pressure on any one spot. In bed, changing position is the primary form of pressure redistribution. When repositioning is difficult, pressure can build up, leading to discomfort and skin concerns over time.; See also: Night repositioning, Shear force

R

Range of motion: How far a joint can move in each direction. Limited range of motion in the hips, shoulders, or spine directly affects which turning techniques work for you in bed. Understanding your available range helps you choose movements that work within your limits rather than against them.; See also: Frozen shoulder, Ankylosing spondylitis, Joint stabilisation
Restless legs syndrome: A condition causing an uncomfortable urge to move the legs, typically worse in the evening and at night. People with RLS reposition their legs frequently, and each repositioning can cause a full wake-up if the bed surface creates too much resistance. A low-friction layer allows leg adjustments with minimal effort.; See also: Night repositioning, Bed friction

S

Segmented turn: A turning technique where you move your body in sections rather than all at once — typically hips first, then shoulders, or vice versa. This reduces the peak effort needed at any moment and allows you to control each phase of the turn independently. Useful for people with limited strength or who need to protect specific joints.; See also: Two-part turn, Log-roll turn, Momentum-assisted turn
Shear force: A force that acts parallel to the skin surface, occurring when the body slides against a surface while the skin stays partially anchored. In bed, shear force happens during repositioning and can contribute to skin discomfort. Reducing friction reduces shear.; See also: Bed friction, Pressure redistribution, Slide sheet
Slide sheet: A low-friction fabric layer placed on or in the bed to reduce the effort needed to reposition. Slide sheets are commonly used in hospitals and care settings but can also be used at home. They work by reducing the friction between your body and the mattress surface, making turns and lateral movements easier.; See also: Transfer sheet, Bed friction, Coefficient of friction
Snoozle: A slide sheet designed specifically for home use and independent sleeping. Unlike clinical transfer sheets that require a carer, Snoozle is a fitted low-friction layer that stays on the bed and lets you reposition yourself with less effort during the night. It is designed to reduce bed friction without the clinical feel of hospital equipment.; See also: Slide sheet, Transfer sheet, Bed friction
Spasticity: Involuntary muscle tightness or stiffness, common after stroke, spinal cord injury, or with conditions like multiple sclerosis. Spasticity can make it harder to bend or extend limbs during bed turns, and sudden movements may trigger spasms. Smooth, slow repositioning on a low-friction surface can help reduce these triggers.; See also: Hemiplegia, Bed mobility, Joint stabilisation
Subluxation: A partial dislocation where a joint slips partly out of its normal position. During sleep, uncontrolled turns can cause subluxation in people with hypermobility or joint laxity. Controlled, staged turning techniques help keep joints aligned through each phase of the movement.; See also: Hypermobility spectrum, Joint stabilisation

T

Transfer sheet: A sheet or pad used by carers to move a person in bed, typically requiring two people to hold the edges and slide the person across. Transfer sheets are designed for assisted repositioning, unlike slide sheets or Snoozle which can be used independently during sleep.; See also: Slide sheet, Snoozle
Two-part turn: A specific segmented turn where you first rotate your hips, then follow with your shoulders as a separate movement. This splits one large effort into two smaller ones and reduces bed shaking, making it especially useful for people who share a bed or who find full turns too demanding.; See also: Segmented turn, Momentum-assisted turn, Night repositioning

W

Weighted blanket resistance: The additional effort needed to turn in bed when using a weighted blanket. The blanket's mass (typically 5-12 kg) presses down on your body, increasing friction and making it harder to rotate, especially mid-turn when the blanket can pin your trailing shoulder or hip.; See also: Bed friction, Two-part turn, Friction seal