The Science of Friction: How Sleep Affects Your Skin and Hair

Most people focus on daytime hair and skin care, but one of the most overlooked contributors to damage happens at night—while you sleep. Friction between your skin, hair, and your sleep surface can cause micro-damage that accumulates over time.

Friction and Skin Health

Why Skin Is Vulnerable at Night

During sleep, skin enters a repair and regeneration phase:

• Collagen synthesis peaks

• Blood flow increases

• Skin barrier permeability rises

This makes the skin more susceptible to shear stress from friction, which can cause:

• Micro-tears in the outer layer

• Increased transepidermal water loss (TEWL)

• Fine lines and wrinkles

• Irritation and inflammation

How Friction Damages Skin

1. Repeated shear stress: Tossing and turning creates dragging against your pillow.

2. Cellular micro-injury: Movement stretches and compresses skin cells.

3. Barrier disruption: Micro-tears make skin vulnerable to irritants.

4. Accelerated aging: Chronic mechanical stress can break down collagen over time.

Friction and Hair Health

Hair Structure and Vulnerability

Hair has three layers:

• Cuticle: Protective overlapping scales

• Cortex: Structural core containing keratin

• Medulla: Inner core (variable)

At night, hair absorbs moisture and swells slightly. Cuticle scales are lifted, making hair mechanically weaker.

How Friction Damages Hair

1. Cyclic friction: Hair rubs repeatedly against fabric.

2. Cuticle lifting: Friction lifts the protective cuticle, exposing the cortex.

3. Micro-fractures: Repeated stress creates microscopic cracks in the hair shaft.

4. Cumulative breakage: Over time, this causes frizz, split ends, and breakage.

5. Static electricity: Rough fabrics increase static and worsen tangling.

The Physics Behind It

• Coefficient of friction (μ): Higher μ = more drag = more damage.

• Cotton and synthetic fabrics have high μ.

• Silk has low μ, allowing hair and skin to glide without drag.

• Humidity and sweat increase friction and micro-damage.

Forces at work:

• Shear force: Lateral drag across surfaces

• Normal force: Pressure from head and body weight

• Result: Microtrauma + moisture disruption → cumulative damage

Why Silk Matters

Silk reduces friction and protects both hair and skin by:

• Allowing hair and skin to glide smoothly

• Reducing micro-tears in skin and hair cuticles

• Maintaining moisture balance and reducing static

• Supporting long-term repair while sleeping

Sleep is when your skin and hair repair themselves. Friction determines whether that repair happens efficiently—or gets sabotaged.

Cove&co Sleep Essentials are designed to minimize friction, protect your skin and hair, and help you wake up looking and feeling your best.