While reading this article about mountaineering boots I found following quote by Ian Nicholson quite interesting:

"When climbing in a double boot, bring the liner in your sleeping bag at night to warm them and slightly dry them, but don't leave them on your feet. It doesn't seem to make that much sense, but wearing them can make your feet quite cold, and just letting them dry in your bag makes them that much more pleasant to put on in the morning."

Emphasis by me and that is the point I am interested in. Did you made similar experiences? And if so, why is this the case?

2 Answers 2


As with clothes you were wearing while you climbed, the liner boots are damp - if not wet from the days activity. Energy is required to evaporate the moisture - this cools you down, including your feet. You get cold from it very easily. Also as most people will feel cold if they have cold feet, so you will feel cold even if you are actually warm enough.

In my experience, removing all clothing used though the day (and ideally putting on dry clothes) will be warmer, and this definitely includes socks and boot liners. It is usually warmer to use you day cloths under your sleeping bag for better insulation than wear them inside the sleeping bag.

Keeping the liner in the bag also cools you down, but you have control over how close to you, and to some extend, how much cooling they inflict on you. Not keeping them in you bag means frozen liner, cold feet, and in cold climates risks frost bite next day.

Edit: Some say using socks for a pillow improves sleep..... :)

  • +1. Dry socks and a big meal are the best things you can do to keep your feet warm all night long.
    – Felix
    Commented Mar 19, 2015 at 19:10

You're sleeping bag only works if you can get it warm. If you wear too many clothes in your sleeping bag, you're not going to fill the loft of your expensive down mummy with cozy warm body heat. This is what can happen if you're wearing your liners in bed, the bag around your feet doesn't warm up.

I think whether or not you get cold toes depends a lot on what else you're wearing under your bag. If you're in your base layer and wearing your liners it shouldn't be an issue, but if you're layered up as well as wearing your liners, then you're not going to warm the bag, and your extremities will pay the price.

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