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Sleeping bags
Introduction
Sleeping bags come in a variety of shapes, sizes and prices. Our guide explains what to look for.
We look at the pros and cons of down and synthetic bags, discuss shape and temperature ratings, and explain how to care for your sleeping bag.
Note: This is a guide only and does not provide test results or brand-specific recommendations.
Sleeping bag basics
Synthetic or down?
The main decision to make is whether to get a synthetic or down bag. Our table below explains their pros and cons. For kids or casual use like weekends away in a bach or crib, a synthetic bag may be all that's needed.
Down sleeping bags are the way to go, particularly if space is an issue. But they're much more expensive - a high-quality down sleeping bag will set you back $400 to $900, whereas a synthetic bag will be more in the range of $100 to $500.
They're also trickier to take care of (see "Caring for your sleeping bag").
Shape
There are two main shapes. Semi-rectangular bags have zips on one side and at the bottom - handy in summer, when you're too hot to be enclosed.
Tapered bags (or mummy bags, as they're sometimes called) don't usually fully unzip and become narrower nearer the feet.
Chris Tews from the Mountain Safety Council says this design is more efficient. He recommends looking for "an insulating flap over the zip" and says a hood "will also add considerably to the warmth".
Temperature ratings
Most sleeping bags come with a temperature rating. But how can you work out which warmth rating will suit you? Unfortunately, temperature ratings are an inexact science and vary from brand to brand. And while a sleeping bag might claim to be "usable" down to -25°C, that doesn't mean you won't be uncomfortably cold at that temperature.
Figure out the likely temperatures you'll be facing on your trip based on location, weather reports and the heights you'll be going to. Then look at sleeping bags that claim to match these and err well on the warm side. If it gets too hot, you can unzip the bag or remove layers.
It may be tempting to save by buying a sleeping bag with a broader warmth rating. Don't give in to this - a sleeping bag should be treated as an investment. You can't change your mind when you're on top of a mountain trying desperately to stay warm.
Caring for your sleeping bag
Sleeping bags are expensive, so you'll want yours to last. Here are a few tips to get the most out of a sleeping bag.
- Buy a silk or cotton liner to prevent your sleeping bag from getting dirty as quickly. These have several advantages: when it's hot, the liner means you don't stick to your bag. It also means you can just wash the liner rather than the bag after a trip.
- Avoid getting your bag wet. Before laying it out, make sure the ground is dry. Try putting your pack liner and other plastic bags under anything your sleeping bag might touch.
- Store your down sleeping bag so it's not stuffed into its storage bag for long periods. If the feathers are highly compressed for too long, they won't expand, reducing the warmth factor and leaving cold spots.
- Down sleeping bags can be hand washed in lukewarm water and mild soap. Make sure you thoroughly rinse - the bag will absorb soap if you don't. If in doubt, ask the person selling you the sleeping bag for advice. You can also buy specialised cleaning products.
Expert tip
Chris Tews from the Mountain Safety Council, recommends drying your down bag in a well-ventilated area: "Initially lay it flat on the floor. Once partially dry it can be hung outside. Warm, windy days provide the best drying conditions."
Chris doesn't recommend using a home dryer - but if you do use one, "place a tennis ball in the dryer with the bag to prevent clumping".
More information
- Mountain Safety Council: www.mountainsafety.org.nz
- Department of Conservation: www.doc.govt.nz
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Report by Tristan Clark