While it’s a convenient categorisation there’s no doubt that the traditional seasonal sleeping bag rating system (where sleeping bags are designated one, two, three, four or even five season) is highly subjective, and the introduction of the standardised EN13537 testing procedure was designed to make things a bit simpler for the consumer. Thanks to the variances in the way people sleep (a hot or cold sleeper, a side, back or front position, male or female, whether you’ve just eaten etc) I’m not convinced that it is. Nonetheless, put simply, the EN13537 Comfort rating is the lowest temperature that a woman can…