What is sleep friction?

Q: How do you reduce sleep friction?

Use a low-friction slide sheet between your body and the mattress surface. A slide sheet like the Snoozle Slide Sheet reduces the coefficient of friction from around 0.45 (cotton-on-cotton) to approximately 0.12, making repositioning 70% easier without lifting.

Q: Can sleep friction cause pain?

Yes. High sleep friction forces you to use more muscular effort to turn, which aggravates joint pain, inflames surgical sites, and triggers spasms in conditions like fibromyalgia and MS. Reducing sleep friction reduces the force needed to reposition, which reduces pain during turning.

Q: How do you measure sleep friction?

Sleep friction is measured as a coefficient of friction (CoF) between fabric surfaces using a standardised pull test. Lower numbers mean less resistance. Cotton-on-cotton is typically 0.40-0.50. Satin is around 0.20-0.25. Engineered slide sheet fabrics like Snoozle measure 0.10-0.15.

Q: Is sleep friction worse on memory foam?

Yes. Memory foam creates significantly more sleep friction than spring mattresses because the foam conforms to your body and creates a depression you must climb out of to turn. A slide sheet counteracts this by reducing surface drag so your hips can glide laterally instead of fighting the foam.

Sleep friction is the resistance between your body and the mattress surface that makes turning, sliding, and repositioning harder during sleep. High sleep friction forces you to lift your body weight to change position — which wakes you up, triggers pain, and breaks your sleep cycle. Reducing sleep friction is the simplest way to make nighttime movement easier without changing your mattress, medication, or sleep position.

This content focuses on comfort, everyday movement, and sleep quality at home. It is not medical advice, does not diagnose or treat conditions, and Snoozle is not a medical device.

Why does sleep friction matter?

Sleep friction determines how much effort it takes to turn over, adjust your hips, or shift your shoulders at night. When friction is low, you can reposition with a small lateral push — often without fully waking. When friction is high, you have to recruit major muscle groups, brace against the mattress, and push hard enough to break contact with the surface. That effort wakes you up.

For healthy sleepers, high friction is an annoyance. For people with arthritis, Parkinson's, fibromyalgia, MS, chronic back pain, or post-surgical recovery, it's a serious barrier to sleep. These conditions reduce the strength, range of motion, or pain tolerance available for nighttime repositioning. Every extra newton of friction means more pain and more waking.

Research on bed mobility shows that impaired ability to turn in bed is rated as the most troublesome nighttime symptom among Parkinson's patients (Neurodegenerative Disease Management). The same repositioning difficulty is reported across arthritis, fibromyalgia, and post-surgical recovery — and sleep friction is the mechanical cause.

What causes high sleep friction?

Sleep friction comes from the contact surfaces between your body and the mattress. Five things drive it up:

1.Memory foam. Foam conforms to your body and creates a valley you must climb out of to turn. Spring mattresses push back; foam absorbs and grips.
2.Mattress protectors. Waterproof protectors add a rubber-like layer that dramatically increases surface grip. Many people don't realise their protector is the biggest friction source — not their sheets.
3.Cotton and flannel sheets. Cotton-on-cotton contact has a coefficient of friction around 0.40–0.50. Flannel is even higher. These fabrics are comfortable but grippy.
4.Clothing fabric. Cotton pyjamas against cotton sheets create a double-grip effect. The friction stacks: body → pyjamas → sheet → protector → mattress.
5.Body weight and moisture. Heavier bodies press harder into the surface, increasing friction force. Sweat increases surface adhesion between skin/fabric and the mattress.

How do you measure sleep friction?

Sleep friction is measured as a coefficient of friction (CoF) — the ratio of the force needed to slide an object across a surface to the weight pressing it down. A CoF of 0.50 means you need force equal to half your pressing weight to start sliding. A CoF of 0.10 means you only need 10%.

Typical sleep friction values (fabric-on-fabric, standardised pull test):

Surface combination	CoF range	Turning effort
Cotton pyjamas on cotton sheet	0.40 – 0.50	High — must lift to turn
Cotton on mattress protector	0.50 – 0.65	Very high — significant grip
Satin/silk sheets	0.20 – 0.25	Low — but uncontrolled (slippery when still)
Snoozle Slide Sheet	0.10 – 0.15	Very low — controlled (stable when still, low drag when moving)

The difference between 0.45 and 0.12 is roughly a 70% reduction in the force needed to reposition. For someone weighing 80kg, that's the difference between needing ~35kg of lateral push force and ~10kg. At 3am with stiff joints, that gap is the difference between turning in your sleep and waking up to wrestle with the mattress.

What is your Sleep Friction Score?

Your personal sleep friction depends on the combination of surfaces in your bed. Use this quick self-assessment to estimate where you fall:

Score 1 point for each that applies:

+1You sleep on a memory foam or hybrid mattress
+1You use a waterproof mattress protector
+1Your sheets are cotton, flannel, or jersey knit
+1You wear cotton pyjamas or a cotton t-shirt to bed
+1You weigh over 80kg / 175lbs
+1You tend to sweat at night

0–1: Low sleep friction. Turning probably isn't your main issue.

2–3: Moderate sleep friction. You may be lifting when you could be sliding.

4–6: High sleep friction. Your bed setup is actively fighting your movement. A slide sheet would make a measurable difference.

How do you reduce sleep friction?

You can reduce sleep friction by changing any layer in the friction stack. From most effective to least:

1.Add a slide sheet. A purpose-built slide sheet sits between your body and the high-friction layers, reducing the CoF from ~0.45 to ~0.12. This is the highest-impact single change. The Snoozle Slide Sheet uses 4-way ultra-low-friction nylon that provides controlled friction — low when you move, stable when still.
2.Switch to smooth sleepwear. Synthetic or silk-blend pyjamas reduce the body-to-sheet friction layer. Avoid cotton and flannel against cotton sheets.
3.Change your sheets. Microfibre or sateen-weave sheets have lower friction than standard cotton percale. But they won't match a dedicated slide sheet.
4.Re-evaluate your mattress protector. If you use a rubberised protector, consider switching to a fabric-topped waterproof protector with a smoother surface.

Where Snoozle fits

The Snoozle Slide Sheet is designed specifically to reduce sleep friction for home use. In fabric-on-fabric testing, it measures a coefficient of friction of approximately 0.12 — compared to 0.45 for standard cotton sheets. That means roughly 70% less resistance when you initiate a turn. It sits between you and the mattress surface, stays in place when you're still, and lets your hips glide laterally when you need to reposition.