On 25 May 2026, Kew Gardens recorded 34.8°C — a provisional record for the highest spring temperature ever measured in the UK, beating one that had stood since 1922. Across southern England and Wales, temperatures reached 32–34°C the same day, with further highs of 35°C forecast across much of England the following day.
But one of the less obvious challenges of this kind of heat is how much the temperature shifts within a single day. While afternoon highs exceed 34°C across the south and reach the high 20s further north, nights this week drop back to 15–19°C across most of the UK — a swing of 15°C or more within the same 24 hours. On a more typical warm summer's day the overnight low falls to 10–12°C, making the variation even greater.
What you wear needs to work across all of it — the cool of the morning, the heat of the afternoon, an evening at home, and a warm night's sleep.
Why heat affects sleep
To fall asleep, your core body temperature needs to drop by roughly 1–2°C. This is a natural part of the circadian rhythm — in the evening, the body begins to shed heat through the skin and extremities, and that cooling signals to the brain that it's time to rest.
When the environment is too warm, this process is disrupted. The body works harder to dissipate heat, heart rate stays slightly elevated, and the brain remains in a more alert state. The result is a longer time to fall asleep, more frequent waking, and less time in the deeper, more restorative stages of sleep. During a heatwave, bedroom temperatures can still be above 25°C at midnight — well above the 16–18°C range that supports comfortable sleep. Many UK homes are designed to retain heat during winter, which can make bedrooms feel especially uncomfortable during short periods of extreme summer weather.
High temperatures also accelerate fluid loss through sweating, even during sleep. Waking up feeling dehydrated or sticky is a sign the body has been working to cool itself rather than resting.
Why fabric matters
Thick jersey, brushed cotton and polyester trap heat against the body regardless of whether you're asleep or sitting at home in the afternoon. Polyester in particular can feel clammy against warm skin. The wrong fabric makes warm weather uncomfortable at any hour.
Viscose has a smooth, lightweight structure that sits softly against the skin and feels less heavy than thicker jersey or brushed fabrics during warm nights. Its fluid drape allows more airflow around the body, helping sleepwear feel lighter and more comfortable in hot weather. The result is less of the overheated, sticky feeling that can disrupt sleep during a heatwave.
Is sleeping naked actually cooler?
It sounds intuitive, but lightweight breathable sleepwear is often more comfortable than sleeping without clothing on warm nights. Soft fabric reduces skin-on-skin contact — particularly relevant if you share a bed — absorbs some surface moisture, and creates a light layer between the body and bedding that can help regulate temperature. During a heatwave, the difference between sleeping in heavy cotton pyjamas and a lightweight viscose set is significant. The difference between the viscose set and nothing at all is much smaller than most people expect.
Best styles for hot weather
SoftConnection makes both sleepwear and loungewear from viscose blends — designed to work from morning through to sleep without needing to change as the day changes around you.
For hot weather, the most useful styles are:
- Short sleeve top with shorts — the most minimal set combination; ideal for the hottest nights and warm afternoons at home. The lightest option when the temperature barely drops by bedtime.
- Short sleeve top with wide-leg trousers — the most versatile combination. Arms stay cool; relaxed trousers are comfortable to move around in during the day and easy to sleep in at night.
- Long sleeve top with trousers — well suited to cooler mornings and evenings, when temperatures drop to 15–17°C even during a heatwave. The right choice for slow starts and relaxed evenings once the day cools.
- Nightdresses and nightshirts — one-piece styles with the least fabric overall. Maximum ease and airflow for the warmest nights when bedrooms haven't had time to cool down.
All styles work equally well for lounging at home and sleeping — the same piece you're wearing at 7am is still the right thing to sleep in that night.
Fit: relaxed, not fitted
Even in a light fabric, a close-fitting silhouette traps heat. For comfort that carries through from day to sleep, look for:
- Relaxed tops — sitting away from the skin rather than body-skimming
- Wide-leg or straight-leg trousers — loose around the thighs and calves, not tapered
- Generous waistbands — wide elastic with real give, comfortable for extended wear
- Open or loose hems — tight cuffs or elasticated ankles retain heat at the extremities
What to avoid
A few choices that feel right in cooler months become genuinely uncomfortable once the temperature rises:
- Fleece and brushed fabrics — designed for warmth; they retain heat regardless of the time of day
- Heavy synthetic fabrics — particularly dense polyester blends — can feel less breathable and more clammy during warm weather
- Tight, body-skimming cuts — restrict airflow and become uncomfortable to sleep in
- Thick jersey and heavy rib fabrics — hold heat in the same way as heavier cotton
Bedding and cooling
Clothing is only part of the picture. Heavy duvets, synthetic blankets and thick mattress toppers retain heat long after the room temperature drops. Lightweight sheets and breathable summer bedding make a real difference alongside light sleepwear — the two work together to help the body cool down rather than working against it.
A few other habits help during a heatwave:
- Keep curtains or blinds closed during the hottest part of the day to reduce heat absorbed through windows
- Open windows in the evening once outside temperatures begin to fall
- A cool — not cold — shower before bed helps trigger the body's natural temperature drop
- Keep water beside the bed; the body continues to lose fluid through the night, and even mild dehydration makes sleep lighter and more disrupted
Care
Viscose blends wash best at 30°C on a gentle or delicate cycle. Avoid the tumble dryer where possible — the fabric air dries quickly and maintains its softness and drape far better without heat.
SoftConnection warm-weather range
SoftConnection uses lightweight fabrics chosen for softness, drape and breathability, including premium viscose blends designed for comfortable everyday wear. The range covers different temperatures and preferences — from the most minimal styles for the hottest nights to relaxed long sleeve sets for cooler mornings and evenings. Designed for real UK home life: comfortable enough to sleep in, easy enough to wear throughout the day.
