I have been enjoying camping in remote locations for a few decades and most times I have provided my own shelter and bedding.
One item that I regard essential for good nights sleep is a suitable sleeping bag.
Second to some form of shelter (not always) the sleeping bag is probably the one item that can make my sleep enjoyable.
Even on very minimalistic trips I have never left it behind.
I have owned countless sleeping bag and currently I have 9 in my wardrobe.
Incidentally all of those sleeping bags are down filled.
I don't own a single synthetic one.
Why?... a couple of reasons.
3 packed-up bags: synthetic (warm-ish), synthetic (cold-ish) and down (warm). Coke can for sizing
When I first started camping (motorcycle days) I was given a synthetic sleeping bag as a present.
Having never owned one before, I was stoked.
It kept me warm at night and that was it.
So why don't I have one now?
My new synthetic sleeping bag was admittedly a bit bulky and used to take up a lot of room on the back saddle of the motorcycle.
With time it became much easier to compress it in the factory storage bag provided.
I thought I was getting good at compressing it but also noticed that it no longer kept me warm on cold night.
My once greatly lofting sleeping bag was now sagging and became thin, all in the short time of about a year.
Eventually I gave up twisting throttles and enjoyed backpacking (bushwalking) more.
My synthetic sleeping bag engulfed half of the space available inside my enormous backpack.
After a couple of outings with experienced bushwalkers I soon realized that synthetic sleeping bags just are not compact nor warm; the other guys all had down filled sleeping bags.
same sleeping bags as in previous photo: out of their compression bag
A down sleeping bag was my next purchase.
I then discovered the other great benefits of a down sleeping bag.
For the same temperature rating my down sleeping bag also weighted half as much.
Much more compact an much lighter: I really liked that.
I also realized that a down sleeping bag had a wider comfort temperature range meaning that it was not too hot during mild nights and still warm enough when the temperature dropped.
It's the natural ability of the tiny down plumes to regulate the comfort level of the sleeper.
Being a natural product down breathes better and will let body moisture escape through the fill better than synthetic.
My down sleeping bags don't suffer from loft loss like my synthetic bag did.
I have one bag that's probably 17 years old and I still use it for the same conditions as when it was new.
If not abused down will really last a long time.
In this comparison I have depicted 3 sleeping bags: two synthetic ones (borrowed) and one down one.
The maroon/black colored one is the down one.
Incidentally is also the warmest.
If size matters (or lack thereof) the photographs speak for themselves.
Just like with my sleeping mats: less is more.
While there is no significant size difference between the bagged (compressed) synthetic bag in the black sack and the down in the orange one, now notice below the two bags out of the compression sack.
The synthetic one offers very little insulation resulting in a comfortable sleep only during warm nights.
The synthetic bags are also much wider in the feet area.
Some might think that a bit roomy is good in balmy conditions, it becomes cold comfort when the sleeping bag should keep you warm.
Despite what technical claims will try to sell you, a sleeping bag is efficient when it traps the body heat provided by the occupant.
And to date there is no better practical insulator than non circulating air.
By lofting down creates a chamber where the air does not move. The thicker this chamber is the warmer the bag.
Furthermore the sleeping bag should prevent the escape of the warm air created by your body.
A wide hood will be unable to trap this warm air and a sleeping bag without a hood is only suitable for mild temperatures.
In essence, to be warm, a sleeping bag should have:
-decent thickness (loft)
-a fitted hood (preferably 3 dimensional)
- a narrow foot area
There are many other additional features that will make a bag even better, but should not lack the above ones.
My pictorial comparison is however biased.
The down sleeping bag is a high end one with 800 loft down, close cut, body contoured.
The synthetic ones are entry level offerings from discount stores.
The price difference is substantial but considering that a well looked after down bag will really last you for years, it probably evens out.
There are better synthetic sleeping bags out there but, in my experience, none come close to the performance of down.
The argument that a wet synthetic sleeping bag will keep you warmer than a down one doesn't fly with me.
I wish to never have to sleep in a wet bag, down or synthetic.
All sleeping bags should be protected in a dry bag where getting it wet should not be an issue.
In twenty five years of camping I am yet to experience a shelter leaking enough to really wet my bag and warrant the use of a synthetic one.
Sure, there are some extreme cases where maybe a synthetic bag would be a better choice; It just does not happen around my part of the woods or stretch of coast :-)
Last but not least: cheap, good... pick one.
Down sleeping bags vary a lot in price. It is worth doing a bit of homework before heading to your favorite retailer. There is a lot of good info/reviews available on line; try to avoid the ones that are commissioned by one manufacturer :-)
