Bedding materials

Cotton, linen, wool, silk, down and synthetics compared. Few good studies exist; choose by whether you sleep hot or cold, and don't expect mite-proof covers to fix allergies.

• Evidence: Weak
• Low effort
• Medium cost
• Works: tonight

Why it matters

Under your covers you create a small climate of your own. When people sleep normally, that space usually sits around 32–34°C (90–93°F) and 40–60% relative humidity [4]. With bedding and clothing on, heat disrupts sleep stages more than cold does: it increases wake-ups and cuts deep sleep and REM, and humid heat makes it worse [4].

Fabrics differ in how much heat they trap and how they handle sweat. That’s the idea behind choosing a fibre. Whether it changes your sleep much has barely been tested [1].

How to do it

1. Decide if you sleep hot or cold. Do you wake sweaty, or kick the covers off? Hot. Do you wake curled up, or reach for socks? Cold. Fix the room first; see room temperature and humidity.
2. If you sleep hot, look for:
   • Sheets: linen, or a cotton weave described as crisp and light (often sold as percale). In one study, 8 young men napping in a humid 29°C (84°F) room woke less on linen sheets than on cotton with a polyester pad [1].
   • Duvet: a lower warmth rating rather than a different fibre. See duvet weight and layering.
   • Pyjamas: light, or none.
3. If you sleep cold, look for:
   • Duvet: down is warm for its weight. In 8 young adults sleeping in a cold room (about 11.5°C, 53°F), a goose down quilt gave more deep sleep than a cotton-filled one [1].
   • Pyjamas: wool. In 17 young adults, wool sleepwear helped people fall asleep faster than cotton at 17°C (63°F) [2].
4. Know what the labels mean. “Bamboo” sheets are almost always rayon (viscose), a manufactured fibre made from plant cellulose. The US Federal Trade Commission says they should be labelled as rayon [10]. Lyocell is a similar plant-based manufactured fibre. Silk, bamboo-derived rayon and lyocell haven’t been compared in sleep studies [1].
5. If you’re allergic to dust mites, talk to your doctor or an allergist about treatment. Don’t rely on bedding covers alone (see below).

Common mistakes

• Paying extra for “cooling” or “temperature-regulating” claims. We found no independent sleep studies of these products. Check what the fabric actually is.
• Assuming down is bad for allergies. In one small study on 12 beds, new synthetic pillows built up dust mite allergen faster than feather pillows over a year [8]. A rare lung condition, feather duvet lung, can come from breathing feather dust; in one series of 13 patients, all had antibodies to goose or duck feathers [9]. If you get a new cough or breathlessness after switching to feather bedding, see a doctor.
• Buying mite-proof covers as your only allergy step. A Cochrane review of 54 trials (3,002 people with mite-sensitive asthma) found no benefit from mite control, including 26 trials of mattress covers, on peak flow, symptoms or medication use [5]. That review is from 2008, and Cochrane now notes it predates current standards. In the largest single trial, 1,122 adults with asthma, mite-proof covers lowered mite allergen at 6 months but didn’t improve lung function or let people cut steroid inhalers [6]. A 2025 meta-analysis of 17 trials came to the same conclusion: these methods reduce dust and mite allergen, but not enough to improve asthma, rhinitis or quality of life [7]. Covers aren’t harmful; just don’t expect them to do the job alone.

Effect on your sleep score

We found no study measuring bedding fibre with wearables.

• Time to fall asleep: wool sleepwear shortened it in two lab studies [2][3]. In adults aged 65 and over sleeping at 30°C (86°F), it was 12.4 minutes in wool versus 26.7 in cotton [3].
• Deep sleep: goose down increased it in the cold-room study [1]. Wool sleepwear gave less deep sleep than cotton at 22°C (72°F), and more at 17°C than at 22°C [2].
• Wake-ups: fewer on linen in the heat in one nap study [1].

How confident: low. These are single small studies.

Evidence

Rated Weak. The 2024 systematic review found just nine studies comparing fibres in sleepwear or bedding, using different methods, fabrics and room temperatures, so the authors couldn’t compare fibres systematically [1]. The ones we checked had 8 to 36 people [1][2][3]. The wool studies were supported by the wool industry, with industry employees among the authors [2][3]. In the 17°C/22°C study, the duvet fibre (wool versus polyester) made no difference to sleep; only the sleepwear did [2].

General information for healthy adults, not medical advice. If you have a sleep problem that lasts, read when to see a doctor. Sources checked 4 October 2026. Spot a mistake? Tell us.