I wear the Smalls Merino Cami every single night. Not because I have to — because nothing else comes close. I've tried cotton, bamboo, modal. They all fall short in the same way: by 3am, I'm either too hot, too cold, or both. With merino, I'm not. I just sleep.
As the founder of Smalls Merino, I'm obviously not a neutral party. But the reason I started this brand is the same reason I wear it to bed: merino wool does things no other fabric does. And the science backs it up.
What Does Merino Wool Actually Do While You Sleep?
Most fabrics are passive. They hold heat or they don't. Merino is active — it responds to your body.
Merino fibres have a natural crimp that creates tiny air pockets, trapping warmth when you're cold. But when your body temperature rises — as it does during sleep cycles — merino releases that heat rather than holding it. The result is a stable thermal environment throughout the night, even as room temperature fluctuates.
A University of Sydney study found that people sleeping in merino wool fell asleep faster and slept up to 15 minutes longer per night than those in other fabrics. That's not a marginal gain — over a week, that's nearly two extra hours of sleep.
Why I Overheat in Everything Else
If you wake up at 3am throwing off the duvet, fabric is almost certainly part of the problem. Here's why:
- Cotton absorbs sweat and holds it against your skin. As you cool down, that moisture creates a chill effect — uncomfortable enough to wake you.
- Polyester and modal trap heat with no breathability. Fine when you get into bed, suffocating by midnight.
- Bamboo is better — it wicks moisture reasonably well — but it doesn't actively respond to body temperature the way merino does.
Merino can absorb up to 35% of its own weight in moisture without feeling wet. Night sweats don't become cold patches. You stay dry, comfortable, and asleep.
The Sensitive Skin Bonus
I have sensitive skin. Most wool would be unwearable next to it — but Smalls merino is 17.5 micron ultrafine. At that fineness, the fibres bend on contact with skin rather than prick it. No itch, no irritation, no waking up scratching.
For anyone with eczema, this matters even more. Synthetic fabrics and some cottons can trigger flare-ups overnight — exactly when your skin is in contact with fabric for the longest stretch of the day. Merino is naturally chemical-free and gentle enough to wear directly against the most sensitive skin, all night.
What I Actually Wear
Every night: the Smalls Merino Cami. Adjustable straps, V-neck, soft enough to forget you're wearing it. In cooler months I'll add the Womens 24 Hour Trouser — which, despite the name, genuinely works as sleepwear. Lightweight enough not to feel heavy in bed, warm enough that I don't wake up cold.
The Daily Mail tested six different sleepwear fabrics across six nights and rated Smalls Merino the best — for temperature regulation, comfort, and sleep quality. I wasn't surprised.
The One Thing I'd Tell Anyone Who Hasn't Tried It
Give it three nights. The first night you'll notice how soft it is. The second night you'll notice you didn't wake up at 3am. By the third night you'll be wondering why you ever wore anything else.
Shop the full Womens Merino collection →
Frequently Asked Questions
Does merino wool help you sleep better?
Yes. A University of Sydney study found that people sleeping in merino wool fell asleep faster and slept up to 15 minutes longer per night. Merino actively regulates body temperature throughout the night, keeping you in the thermal comfort zone that promotes deep, uninterrupted sleep.
Is merino wool good for sensitive skin?
Yes. Ultrafine merino (17.5 micron or finer) is soft enough to wear directly against sensitive skin without irritation. The fibres bend on contact with skin rather than prick it, making it itch-free and eczema-friendly. It's also naturally free from synthetic chemicals.
Is merino wool too hot to sleep in?
No — this is the most common misconception. Merino actively regulates temperature, releasing heat when your body warms up rather than trapping it. It's the reason merino works year-round, not just in winter. Most people who overheat in bed find merino solves the problem rather than making it worse.
What is the best fabric to sleep in?
Merino wool is the best fabric for sleep for most people. It actively regulates body temperature, wicks moisture without feeling wet, and is naturally soft against sensitive skin. A University of Sydney study confirmed merino sleepers fall asleep faster and sleep longer than those in other fabrics including cotton.
Is merino wool better than cotton for sleepwear?
Yes, for most people. Cotton absorbs moisture and holds it against the skin, creating a chill effect as you cool down during the night. Merino wicks moisture away and actively responds to body temperature changes — keeping you comfortable without overheating or chilling.
Can you wear merino wool in summer?
Yes. Because merino regulates temperature rather than simply insulating, it works in warmer months too. The Smalls Merino Cami is lightweight enough to wear through spring and summer — breathable when it's warm, and just enough warmth when the temperature drops overnight.