Why are baby sleeping bags so thin?

[CuppaTeaJanice]

I know babies can't regulate their temperature very well and you have to be careful they don't overheat, but why is there such an enormous difference in the thickness of baby sleeping bags and adult duvets? I'm snuggled up in my winter pyjamas under 13.5 tog of duvet, and poor little DD is shivering away in her 2.5 tog sleeping bag. I have to use an extra blanket which kind of defeats the point of having a sleeping bag in the first place (ie so she can sleep at the top of the cot next to me, not feet-to-foot).

Why aren't the bags thicker? I don't think I've ever seen one warmer than 3 tog. After all, the usual advice for dressing babies during the day is 'what you are wearing, plus one more layer.' Why does the opposite seem to be true at night?

I think the idea is that it's warmer when they're smaller/closer like an adult sleeping bag. What's the temperature in your house at night? Those things are designed for 17 degrees. If it's a bit colder I've been known to layer DS up. Long sleeve vest plus babygro, sleepingbag, cardigan on top.

It's because the bags are 360 degrees so they retain heat better. I've never understood it either but it works, even though it does look like they need another layer or two.

It's 19.3C in the bedroom at the moment. It does go a bit cooler at night but not usually less than 17.

My sleeping bag is a lot thicker than 2.5 tog. Not as thick as a duvet, but at least 3 times as thick as DD's.

the gro.co.uk website says this:

Health professional guidelines recommend that Baby Sleep Bags should be ?lightweight'. Our own research and our mounting body of "parent testimonials" confirm that our 2.5 Tog Grobag Baby Sleep Bags are ideal for the UK climate and for the recommended nursery nursery temperatures of 16°C to 20°C. A Baby Sleep Bag surrounds the baby, providing insulation from both below and above, and also a warm pocket of air around the baby.
Because of the low tog rating, Grobag Baby Sleep Bags also provide great versatility throughout the year, simply by adjusting the level of your baby?s nightwear. When the weather is very cold, simply add more clothing (this could include a sleepsuit, socks and even a cardigan). When the weather is warmer, or perhaps if your child is unwell, you can remove layers of clothing while still keeping your baby at the right temperature.
Remember: never use a duvet or quilt with a Baby Sleep Bag.

There are thicker ones out there. I saw this last month and it's definitely heavier/thicker but it has zip off sleeves and a removable liner and all sorts. Definitely an investment piece maybe you can find something comparable a bit cheaper though.

Thanks - I guess it makes sense about the pocket of warm air in an enclosed bag (especially if baby farts as much as DD!). Presumably the thicker bags are for colder Scandinavian countries.

By the way, how do you type the degrees symbol? I can't see a button for it on my keyboard.

I copied and pasted - have no idea how to do the symbols myself!

This used to confuse me until someone gave me the analogy of a mouse sleeping under a 3in square of normal duvet - it would be like sleeping under an entire feather bed . The thickness needed for warmth is proportional to size, kinda thing...iyswim....

cuppa to get the degree symbol highlight the o then ctrl D and select superscript.

I find them thin too but ds wears vest, sleepsuit and has a fleecy blanket on top and seems fine.

ergoPouch has a 3.5 Winter Tog Range if you ever needed something warmer.

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