Choosing the Best Sleeping Bag For Your Travels
This remains a solid guide and the structure holds. Three things are worth updating.
Temperature ratings are now standardised and you should read the right number. Bags sold in Europe and most sold in the US now carry an EN or ISO rating with two figures: comfort and limit. Comfort is the one to use if you sleep cold or are a woman, for whom the standard's own test assumes a colder sleeper; limit is for a warm sleeper. The old single "rated to" figure was marketing and is what made 2010-era bags feel optimistic.
Down versus synthetic has shifted toward down, because treated down changed the calculus. Hydrophobic down resists moisture far better than untreated, which removes most of the old argument for synthetic. Down is still lighter, packs smaller and lasts decades if looked after; synthetic is still cheaper and still the better bet if it will be permanently damp.
And ask where the down came from. This did not exist as a question in 2010. The Responsible Down Standard and similar schemes certify that birds were not live-plucked or force-fed, and most reputable brands now use certified down. It costs nothing extra to choose.
For travel specifically, as opposed to camping, the original advice still stands and gets forgotten: most hostels and guesthouses supply bedding and many will not let you put a sleeping bag on their mattress. A silk or cotton liner weighs 200g, packs to the size of an orange, and covers the actual use case. Carry the bag only if you are camping, on night trains, or heading somewhere cold in the shoulder season.
Part of the guide to sleeping bags and pads.