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Which jimjams really are the cat's pyjamas? Our sleepyhead puts velvet, silk and pure wool to the zzzz-test

  • Temperatures may drop below zero in Britain next week and there could be snow
  • Studies suggest woollen pyjamas help wearers drop off faster and sleep longer
  • Alice Smellie spent six nights testing nightwear made from six different fabrics 

 The cold snap has definitely hit. Temperatures may drop below zero in some parts of Britain next week, and the Met Office has indicated there could even be snow — so it’s important to wrap up warm.

But the most important question over what to wear this winter has to be what nightwear to choose, as your body temperature is linked to the quality of your sleep.

Studies now suggest woollen pyjamas are conducive to the most restful night, with wearers dropping off faster and sleeping longer. The research used PJs made of soft merino wool, which is great at thermoregulation, keeping our temperatures constant. It also supports the transfer of heat from our core to our hands and feet, helping us drop off faster.

‘Wool helps to maintain you in your thermal comfort zone as it is naturally good at managing temperature and humidity. It wicks and absorbs moisture away from the body — up to 36 per cent of its own weight,’ explains Dr Paul Swan, one of the research co-authors.

But how well do jim-jams made from other materials perform? ALICE SMELLIE spent six nights testing nightwear made of different fabrics with the Sleep Cycle sleep tracker, and rated each item, while Dr Swan commented on the materials.


Cyberjammies Fiona Check Nightshirt, £29,

This brushed cotton nightshirt feels soft. I mostly wear cotton nightwear, but it’s often trousers and a camisole, so I am charmed by the compliments from my daughter Lara, ten, who hasn’t seen my legs in months.

Cotton: Cyberjammies Fiona Check Nightshirt, £29

Cotton: Cyberjammies Fiona Check Nightshirt, £29

SLEEP EASY? I am like the Princess and the Pea when it comes to bedtime, using ear plugs, an eye mask and many layers (a duvet, a cover, a fur cover and a Wool Room mattress topper), as well as three down pillows. In the past couple of weeks I have also fired up my electric blanket. I have no intention of getting cold.

The three-quarter-length sleeves mean I can stick my arms out of the duvet without them cooling down. It takes a few minutes for my feet to warm up, after which I am the perfect temperature. I am asleep by 11pm and drift awake at 6am refreshed. My sleep app suggests my sleep quality was 100 per cent, and I would pretty much agree with that assessment.

EXPERT verdict: Like wool, cotton is a natural fibre, composed of carbon, water and oxygen. It can absorb up to 22 per cent of its weight in moisture. The fibres are hollow rather than solid, so it isn’t as warm as wool.




Sainsbury’s Peach Check Print Pyjamas, £16,

THESE thick polyester pyjamas feel shiny and slippery, and are a bit tight around the thighs. I always buy a size too large in nightwear, so this is irritating.

SLEEP EASY? I am in bed at 10pm. I’ve been forbidden from drinking alcohol as it affects sleep quality, so I read and am asleep by 11pm.

Half an hour later I wake, boiling. I lie fuming for an hour, doing cooling down techniques: sticking a leg out of the duvet and turning my pillow over. Eventually, I give in and take off the top. I sleep for five hours before waking at 6am. I spent eight hours in bed, but I am tired and in a bad mood all day.

Polyester: Sainsbury’s Peach Check Print Pyjamas, £16

EXPERT verdict: An oil-based fibre, polyester has poor moisture management properties. It can only absorb about 3 per cent of its weight in water. I view sleeping in polyester as a little like sleeping in a pressure cooker.

Being typically non-biodegradable and composed of mined fossil carbon, I consider it a pollution risk. You may be warm, but synthetics make you sweaty in bed.




Debenhams Lounge and Sleep Floral Print Chemise, £12.50,

THE soft, loose viscose nightie has a pretty pattern and enough lace to stop it being frumpy.

SLEEP EASY? I am very comfortable; there is nothing constraining my arms or legs. It takes a while to warm up my limbs, but I am confident of a good night’s sleep.

Viscose: Debenhams Lounge and Sleep Floral Print Chemise, £12.50

Viscose: Debenhams Lounge and Sleep Floral Print Chemise, £12.50

Unfortunately, a squirrel (actually, this is definitely a rat, but nobody likes to think of rats scuttling overhead at night) has decided it’s time to play games in the attic. So the sleep tracker shows I am awake until 12.30am.


When the squirrel/rat finally finishes its business, I fall asleep until just after 6am.

Had it not been for the in-house wildlife, I’m pretty sure I would have slept far better. I can’t blame the nightwear.

EXPERT verdict: Viscose rayon was one of the first synthetic fibres, marketed as artificial silk. It has a natural base of cellulose from wood pulp, and has good moisture management properties similar to those of cotton.




Silk Devore Pink Pyjamas, £189,

The most vibrant pyjamas I’ve seen, in bright pink with blue trim. They cost more than most of my dresses. I feel like Noel Coward in a smoking jacket. My husband does a double-take.

SLEEP EASY? I sink into bed enjoying the feel of expensive fabric against my skin. But at 2am I wake up hot. I wriggle around and throw bits of duvet off, and after half an hour I take off the top. My sleep quality shows as 89 per cent, but I suspect that’s because I lie still to try to go back to sleep.

Velvet: Silk Devore Pink Pyjamas, £189


Smalls Merino Evercami in Misty Rose, £62.95, and 24/7 trousers in Navy, £134,

This seems like an expensive way to get a good night’s sleep, but there is an excellent case for wearing merino wool. These aren’t the most beautiful items, but wearing them is like sinking into a cloud, with no tight seams or buttons.

SLEEP EASY? The best night’s sleep of the week. The next day is the sort of stressful one which would normally have me tossing and turning, but I don’t stir until my alarm goes off. The only reason my sleep tracker doesn’t show 100 per cent is because I have to rise an hour earlier than usual. I cannot recommend these jim-jams highly enough — and it proved the wool studies right.

Wool: Smalls Merino Evercami in Misty Rose, £62.95, and 24/7 trousers in Navy, £134

Wool: Smalls Merino Long Sleeve in Forest Green Rose, £115, and 24/7 trousers in Navy, £134

EXPERT verdict: The research shows that merino wool helps you to fall asleep, and maintains sleep by managing your skin temperature and the humidity.

We found students in their 20s who wore pyjamas made from merino wool rather than cotton fell asleep four minutes faster, and stayed asleep longer — yielding nearly two days of extra sleep in a year. A second study of older adults confirmed these findings.



Tender Is The Night Silk Pyjamas top, £180, and bottoms, £210,

Almost £400 for a pair of silk and cotton pyjamas is so much money that I hardly even dare to put these on. They are stylish and I toy with the idea of wearing the bottoms as evening trousers. But for bed? It seems a waste. I sense I am not really the target demographic.

Silk: Tender Is The Night Silk Pyjamas top, £180

SLEEP EASY? These are comfortable and I fall asleep quickly. I wake up with warm legs at one point and can’t go back to sleep, but this is hardly the fault of the breathable silk, so I read for an hour.

EXPERT verdict: Silk has all sorts of natural properties. It’s designed in nature to be light and strong, but it is not as good at managing moisture as wool. However, it has other helpful properties; it’s a very thin, smooth fabric, which is good at conducting heat away from the body — this makes it great for sleeping on a hot night, and less so in a colder country.




It’s not just wool pyjamas which can help you sleep better. A wool duvet is naturally hypoallergenic, and helps your body regulate temperature. ‘We’ve seen a 45 per cent growth in our wool bedding items in the last couple of months; it’s the most sustainable of natural fibres,’ says Chris Tattersall, managing director of The Wool Room.

THE WOOL ROOM: Classic Wool Medium Duvet, from £44.79 for a single, These duvets are made from 100 per cent British wool, with a 200 thread count. They are approved by Allergy UK and naturally mould, mildew and dust-mite resistant.

Devon Duvets: From £100 for a lightweight single duvet, These are handmade in Devon with a 260 thread count. The wool hasn’t been bleached or chemically treated, so it’s more resistant to dust mites, meaning it might be ideal for allergy sufferers.

Soak and Sleep: Luxury wool duvets from Australia and New Zealand, from £32 for a single, The cotton cases are unbleached and the duvets come in four warmth levels — summer, spring/autumn, winter and all seasons.