Sleep Sack FAQs

Yes — a wearable blanket is the standard way to keep a baby warm while following safe-sleep guidance. The AAP recommends a firm, flat sleep surface with no loose bedding, and suggests layers of clothing or a wearable blanket instead of blankets in the crib. The NHS lists a baby sleeping bag among its recommended options.

A sleep sack cannot be kicked over the face or bunched around the head, and it keeps warmth steady through the early-morning hours when rooms are coldest. For advice about your own baby, speak to your pediatrician.

No product prevents SIDS, and we will not claim otherwise. Current guidance does recommend a crib free of loose bedding, and a sleep sack is a way to meet that without leaving your baby cold. Overheating is listed as a risk factor, which is why matching the TOG to the room matters more than buying the warmest sack available.

They suit different stages rather than being safer or less safe. A swaddle restricts the arms and must be stopped as soon as your baby shows signs of rolling — the AAP puts that at around 3 to 4 months. A sleep sack leaves the arms free, so it works from birth and keeps working after rolling starts.

If you are mid-transition, our guide to moving from swaddle to sleep sack walks through it step by step.

Three situations. Once your child can climb out of the crib, once they have outgrown the largest size, and any time they are in a car seat or stroller harness — a sleep sack must never sit between a child and the harness straps. Outside of those, the question is which TOG, not whether.

No fabric is inherently fireproof, and we would rather say that plainly than imply otherwise. Natural fibres like organic cotton and camel wool give real comfort and breathability, but as with all baby sleepwear, our products should be kept away from open flames and other heat sources.

The practical version: keep candles, portable heaters and similar hazards out of the room where your baby sleeps. That habit does more for safety than any fabric claim.

Every Kaiya Baby sleep sack carries a temperature-sensing sticker so you can check without touching your baby: blue means a little cold, yellow means comfortable, orange or brown means too warm. Hands and feet are normally cooler than the body and are not a reliable signal.

If you are checking by hand, use the chest or the back of the neck. Damp skin, flushed cheeks and fast breathing mean too warm; a cold chest means add a layer or move up one TOG.

TOG measures thermal insulation — how much warmth a fabric holds — not how thick it is. A higher TOG means a warmer sack, and each rating matches a room-temperature range rather than a season or age. It is why two sacks with the same rating can feel very different in the hand and still keep a baby equally warm.

Match the rating to your room’s lowest overnight temperature. Our four ratings run end to end with no gaps, so whatever the thermometer reads, one of them covers it: 0.5 TOG for hot days at 75–80°F (24–27°C), 1.0 TOG for balanced warmth at 68–75°F (20–24°C), 2.5 TOG for cooler nights at 61–68°F (16–20°C), and 3.5 TOG for chilly weather at 57–61°F (14–16°C).

Note that 61–68°F (16–20°C) — our 2.5 TOG range — is also the nursery temperature recommended by the NHS and The Lullaby Trust.

Later. Most bedrooms feel comfortable when you put your baby down and then lose several degrees before dawn, and that early-morning low is what your baby actually sleeps through. Leave a thermometer in the room for a couple of nights and choose the TOG for the lowest reading, not the first one.

Choose the lower TOG and adjust the layer underneath. A 1.0 TOG sack with warmer pyjamas is easier to get right than a 2.5 TOG sack in a room that is slightly too warm for it — and a layer can be removed at 3am, a sleep sack cannot.

One layer in most cases, chosen by where you are inside the TOG band. Near the warm end, a short-sleeve bodysuit; near the cool end, a long-sleeve bodysuit with footed pants. The AAP sums it up as roughly one more layer than you would wear in the same room.

No hats indoors — a covered head is the fastest route to overheating. Full breakdown by temperature in What to Wear Under a Sleep Sack.

Most families end up with two: one for the warm half of the year and one for the cold half. Which two depends entirely on your home — a centrally heated apartment may never leave the 1.0 TOG range, while an older house might need 1.0 and 3.5, and nothing in between.

By height and weight, not by age — babies of the same age vary a lot, and fit is what keeps a sleep sack safe. Our 0–6 month size fits 21–27" (53–69 cm) and 7–18 lbs (3–8 kg); 6–18 months fits 26–33" (66–84 cm) and 16–27 lbs (7–12 kg); 18–36 months fits 32–39" (81–99 cm) and 25–36 lbs (11–16 kg).

If your baby sits between two sizes, choose the smaller one and replace it sooner — see the full Size Chart Guide.

Snug above, roomy below. The neckline should sit close without slipping up toward the chin; the armholes should feel secure, and there should be plenty of room through the hips and legs for kicking, stretching, and rolling. Our sacks use a drop-crotch cut so the lower body stays free without adding fabric around the chest.

No. Extra fabric around the chest and neckline is the thing to avoid, and it is what makes a too-large sack unsafe. Extra room below the hips is fine. Buying the size that fits now and replacing it later is the right call, even though it feels less economical.

When your child outgrows the largest size, starts climbing out of the crib, or moves to a toddler bed — whichever comes first. There is no age at which a sleep sack becomes unsuitable; many children keep using one well past their second birthday.

Two is the practical minimum — one in use while the other is in the wash, because spit-up and leaks do not wait for laundry day. A third makes sense if your baby attends daycare, you travel, or your room temperature swings enough to need two different TOG ratings in the same month.

Both the outer shell and the lining are 100% GOTS-certified organic cotton, with the filling sealed between them. The 1.0, 2.5, and 3.5 TOG sacks use a filling of 30% camel wool and 70% SORONA® polyester: camel wool buffers temperature swings, and SORONA® keeps the sack light so a warm rating does not mean a bulky garment. The 0.5 TOG is unfilled — 100% GOTS-certified organic cotton and nothing else, which is what makes it the lightest rating we make.

Three, and they cover different things. GOTS certifies our organic cotton across the whole supply chain — how the cotton is grown, which dyes and finishes are permitted, and fair labour practices — which is what separates a certified product from one merely described as “natural”. Our sleep sacks are SGS-certified for material safety. The ClimaCuddle® line is certified to OEKO-TEX® Standard 100.

Across the whole sleep range, every product is verified free from lead, phthalates and formaldehyde, and holds a skin-friendly pH suitable for sensitive skin. Each style is also tested for seam strength, dimensional stability, shrinkage, pilling resistance and colour fastness, and edges, trims and sizing are assessed against suffocation hazard guidelines. Full detail on our Product Safety page.

They are different product categories, not two versions of the same thing. The sleep sacks use a GOTS-certified organic cotton shell with a camel wool and SORONA® filling, in four TOG ratings. ClimaCuddle® is our 51% Rayon from Bamboo / 49% Merino Wool fabric, used in swaddles, bodysuits, and rompers — the layers worn under a sleep sack. There is no ClimaCuddle® sleep sack.

Not in these blends. Itch comes from fibre diameter rather than from wool as such — the coarse fibres in a traditional jumper are two to three times thicker than merino. In the sleep sacks, the wool sits inside the filling, enclosed between the cotton shell and lining, so it is not in contact with your baby at all. ClimaCuddle® bodysuits and rompers are worn next to the body, and there the bamboo rayon side faces inward.

They do different jobs, and the honest answer is that the best fabric depends on your baby. Organic cotton is the most durable and handles frequent hot washes. Bamboo rayon is softer and drapes better but wears faster. Merino and camel wool regulate temperature across the widest range but cost more and need a gentler wash.

Choose by how your baby moves at bedtime. Sleeveless for warm rooms and babies who run hot. Long Sleeve once the room drops below 68°F (20°C). Walker once your baby stands, cruises or walks before sleep. Sleep Suit Sack 3-in-1 if you want one piece that works as a sack, a walker, and split-leg for the stroller.

Not every style exists at every rating, because some combinations do not make sense. Sleeveless is available in 0.5 and 1.0 TOG only — a room cool enough for 2.5 TOG is a room where arms should be covered. The 3-in-1 comes in 1.0 and 2.5 TOG. Long Sleeve and Walker are available across all four ratings.

Sleeves are not a safety question — the safety rules are about the neckline and armholes. What sleeves change is layering: below 68°F (20°C), covered arms let you use one lighter layer underneath instead of two bulky ones. Above that, sleeveless gives you more room to fine-tune with what goes underneath.

A temperature-sensing sticker that shows at a glance whether your baby is comfortable; fold-over cuffs on the long-sleeve styles so you can cover the hands on cold nights; a breathable underarm panel; a full-length zipper; and a drop-crotch cut that leaves room for hips and legs.

Zip the sack all the way up, put it in a laundry bag, machine wash at 40°C (104°F) with a mild detergent, then tumble dry on low or line dry. No fabric softener, no bleach, no soaking, no dry cleaning. Low heat iron if needed. That routine covers 0.5, 1.0, 2.5 and 3.5 TOG.

On the filled sacks — 1.0, 2.5 and 3.5 TOG — there is one extra step: take the sack out while it is still damp, unzip it, shake it out by the shoulders and break up any clumps you can feel before it dries. The 0.5 TOG is unfilled, so its routine ends when it is dry. Full detail in our Washing & Care guide.

It can, if the filling dries compressed. A filled sleep sack holds warmth in the still air trapped inside the filling rather than in the fabric itself, and every wash cycle presses that filling down. If it dries flat it sets flat, and over enough washes the sack drifts away from the TOG it was made for.

Two habits prevent it. Wash the sack only when it is visibly soiled or after a leak — worn over a base layer, it needs washing less often than the clothes underneath. And open the filling back up before it dries: unzip, shake it out by the shoulders while damp, then tumble dry on low with a couple of wool dryer balls, or line dry fully unzipped with a fan on it.

All three protect the filling. Softener leaves a coating on the fibres, and coated fibres do not spring back the way bare ones do. A long soak lets the filling take on water unevenly and shift position while saturated, and it does not always move back. Dry cleaning solvents strip the natural oils from wool and leave the fibres more brittle — the opposite of what a filling needs.

Work on the shell only, and keep the wet area small. Lay the sack flat so the marked panel is supported, dab rather than scrub with a damp cloth and a little mild detergent, then rinse the same way with a second cloth wrung out in plain water. Let it air dry fully before storing. A patch that gets soaked and rubbed hard drives water into the filling, and that patch dries compressed while the rest stays lofted.

ClimaCuddle® items are the exception — rubbing a wet wool blend in one spot is the exact motion that makes wool contract, so a full cold wash is safer there.

Differently from the sleep sacks. Close any zips or snaps, use a laundry bag, and machine wash cold at or below 30°C (86°F) on a gentle or wool cycle with a mild detergent and no bleach. Then lay flat to dry — not tumble dried, even on a no-heat setting.

The Merino is why this routine is stricter. Wool fibres have a scaled surface, and agitation while wet makes those scales interlock so the fabric contracts and stays contracted. The sleep sacks tolerate low heat because their wool sits inside the filling between a cotton shell and lining; ClimaCuddle® knits the wool into the surface fabric, so a dryer acts on it directly.

When it is visibly soiled or after a leak — not on a fixed schedule. Worn over a base layer, a sleep sack usually stays clean longer than the clothes underneath. Between washes, hang it open over a chair for a few hours to air it out. On a filled sack, every cycle you skip is loft you keep.

Not required. If you would rather, a first wash is no different from any other — use the routine above. The 0.5 TOG sacks are 100% GOTS-certified organic cotton; our sleep sacks are SGS-certified; and the ClimaCuddle® fabric is certified to OEKO-TEX® Standard 100 in the class used for baby products.

Yes, we ship all over the world. Shipping costs will apply, and will be added at checkout. We run discounts and promotions all year, so stay tuned for exclusive deals.

It depends on where you are. Orders processed here will take 5-7 business days to arrive. Overseas deliveries can take anywhere from 7-16 days. Delivery details will be provided in your confirmation email.

Yes. We offer a full refund within 45 days of purchase on any unwashed, unaltered item in its original condition — no complicated process, just contact our customer service team. If you are returning for a personal reason such as sizing, you cover the return shipping; if we sent the wrong item, we cover it.

Sizing is the most common reason for an exchange, and we would rather you had the right fit than the right size on paper. Full terms on Returns & Exchanges.

Yes — see our embroidery service. Note that personalized items normally cannot be returned, so check the size chart carefully before ordering.

Email us or use the contact form— we answer product and sizing questions directly, and we would rather help you pick the right TOG before you order than process an exchange afterwards.