If you aren't wearing all of your clothing inside of your sleeping bag, you're carrying too heavy of a sleeping bag. (That is, if you're actually carrying it. If you're car camping, then the extra weight doesn't matter.)
I respectfully disagree with this. Here's my rationale:
Heat vs Temperature
Heat is the excitation of molecules. The more heat, the more excited they are. Lake Superior, at 55 degF has FAR more
heat than a cup of boiling water. Temperature is really kind of a 'density of heat'. The amount of molecule excitation in a confined area. The cup of boiling water has a far greater
temperature.
What we REALLY want when we sleep is for the air temperature next to our skin to be comfortably high in temperature. To do this, we trap excited air (heat) in dead air space near us. Generally, our heavy insulated jackets and our sleeping bags contain the most loft to do this the most effectively. So, to get that high temperature air nearest you, sleeping bare skinned or with a single base layer is the best way to get that heat closest to you.
Wearing extra layers of clothes is ultimately separating you from the most effective portion of your insulation.
The heavy layer jacket (assuming it isn't heavy in weight) can be put atop the sleeping bag for slightly more insulation. You should NOT put all your clothes on top of the bag because this will compress the insulation in it, making less dead air space volume.
As always, more material between you and the ground is advantageous. If you are in a tent, use the extra clothes as a ground cloth (between two sleeping pads works best), or as a pillow.
Some more winter camping lessons:
- PRIMARY: Have a realistic understanding of your capabilities, skills, and gear; and weigh them against the expected weather. If you're a 60 year old with asthma, going on a winter camping trip with 6' of snow, and don't have snowshoes or skis, you should consider altering your travel expectations.
- Bring chapstick.
- Embrace modern materials for clothing and shelter that are hydrophobic. Wool is also superb.
- Your tent keeps the wind, snow, and rain out. It does NOT keep you warm. Your sleeping bag does that.
- As soon as your tent is up, lay out your sleeping bag to give it plenty of time to loft up.
- Snow is a fantastic building material. Use it to create wind barriers, and other camp necessities.
- A cheap plastic sled is an amazing tool for working with snow.
- Do NOT use a ceramic water filter. The element can crack when it freezes.
- It gets dark earlier. Ensure enough time to make camp. At least 1.5 hrs is recommended until you become seasoned at it.
- Everything takes longer in winter.
- Your insulation layers thermally separate you from the ambient air. If you make a fire, unzip or shed layers to let the warmth of the fire get to you.
- Collect 4x more firewood than you think you'll need.
- Save firewood for the next morning.
- Warm drinks will make you warm. Duh. Drink them, even if it's just hot water. It is free heat!
- Warm drinks will make you go pee and it is cold outside. Go before you turn in for the night. No matter what. Have a pee bottle for your shelter. It sounds gross, but unzipping your bag is inconvenient. Putting on clothes and boots to leave the tent is even more so.
- Always wear a wool hat when sleeping. Conventional thinking is that it augments your bag's temp rating by 5 degrees when doing so.
- If you get chilly in your sleeping bag, getting up and going pee will make you warmer in the long run. Your body doesn't need to expend energy trying to keep a bladder of urine warm.
- If you still feel chilly, you can do some exercises, such as leg lifts, in your bag. Steady and moderate. Don't sweat, just generate core heat.
- A candle lantern hung in your tent can help raise the temp in it slightly as well as promote airflow out of the tent. This is very useful in reducing condensation.
- Keep a bottle of water with you at night. Do your best to keep it from freezing. Liquid water is far easier to heat than ice.
- When you wake up, get busy doing something immediately. Start the fire if it hasn't been done, or get some more wood for it. You have to generate more warmth for yourself.
- When hiking, beware ice or streams that may be covered in snow. Know the terrain.
- When hiking, be exceptionally careful of swamps or bogs. The bio-energy created in them is enough to keep them from freezing as much as other areas, and can become very treacherous to walk across.
- Leave your itinerary with someone. Have a "you'd better call in the rescue" date/time with someone if they haven't heard from you or haven't been able to reach you.
- Move sunglasses from the 'nice to have' category into the 'necessity' category. Snow blindness is a real thing, and not just a danger on bright sunny days.
- Headlamps are better than flashlights. Consider a glow-stick for longer duration lighting needs.
- ALWAYS ALWAYS ALWAYS have an emergency whistle ON YOU always.
- Keep batteries on you in interior pockets to preserve their longevity. Lithium Ion are lighter and withstand temperature fluctuations better.
- Know how to build at least one natural shelter, such as a quinzee.
Some gear I like and why:
- Smartwool socks: $18 for socks is ludicrous. Until you try them on. Expedition weights are like warm slippers. Hiking weight are great for cold weather hiking. These are good at getting moisture away from your feet and up and out.
- Klean Kanteen steel bottle: Single wall, not the dual wall insulated one! Can serve as a pot to heat water, and is durable.
- Stevenson Warmlite Tent: A bit eccentric, but a great tent for winter camping. I've had mine 20 years and probably approaching 500 bag nights. No issues with it (other than I want a new color now, so if you like purple, let me know and I'll sell you mine so I an get a different color).
- Trekking Pole: I have found many uses for a trekking pole aside from walking. They are worth it!
And some Wisdom:
- Appreciate who you are there with, and their contributions to the camp. That fire was teamwork. Acknowledge it.
- Do more than you want to. There's lots to do and others may be struggling with the work and the cold. Especially if you are experienced, help the inexperienced as much as they'll let you and as much as you are able.
- Respect the season and all it brings. Stay aware of your group's conditions.
- Leave No Trace. A bit hard in the winter with tracks, but the principles of respecting the land always apply.