Sleeping Bags are typically categorised into Season Ratings, but these ratings should only be considered as a guide and not a guarantee of the bags suitability for your needs.

The following table shows what is generally meant for each season rating.

You will typically see two temperature ratings quoted: the Comfort Temperature Rating and the Extreme Temperature Rating. What are they? What do they mean?

THE COMFORT TEMPERATURE RATING - is shown as a range e.g. +12°C to +25°C. The range is generally understood to refer to the ambient temperature around you. The first temperature quoted in this range is the lowest the manufacturer considers you will remain comfortable in. Naturally, the second value is the highest temperature that they consider you will remain comfortable in.

THE EXTREME TEMPERATURE RATING - is a single value and is generally understood to be the coldest temperature that an experienced user should use the sleeping bag in.

Although all sleeping bags have temperature ratings you should bear in mind the following:-

• Notions of warmth and what is a comfortable sleeping temperature are subjective. Be aware of this and let your knowledge of your own personal requirements influence your decision.

• There are no standard measurements of temperature ratings among sleeping bag manufacturers. Use the ratings as a reasonable guide only.

From the beginning of 2005, sleeping bags that meet the standard will display 4 temperature ratings:

• Upper Limit - highest temperature at which a standard MAN would have a comfortable nights sleep without sweating.
• Comfort - lowest temperature at which a standard WOMAN would have a comfortable nights sleep, lying on her back and relaxed.
• Lower Limit - lowest temperature at which a standard MAN in a rolled up body posture would have a comfortable nights sleep.
• Extreme - temperature below which a standard WOMAN could expect strong sensation of cold and maybe actual physical injury from cold (e.g. frost bite or hypothermia).

GOOSE DOWN - is a natural insulator and is preferred to down from ducks. The goose feathers have softer spines and are therefore better for comfort. There is also less likelyhood that they would pierce through the fabric that contains them.

Lets list the positives first.

• Lasts longer than synthetics (but requires greater looking after for this to remain true)
• Is lighter than synthetic materials but offers excellent warmth ( excellent warmth to weight ratio )

• Down absorbs moisture readily and loses all its insulating qualities whilst wet. It takes a long time to dry.
• Down filled sleeping bags are generally more expensive but if cared for properly they can last a lifetime and thus can be seen as having outstanding long-term value.

The positives for synthetic fill are

• They still provide some insulation when wet and dry fairly quickly especially when compared to down fill. This can also mean they are easier to clean ( most are machine washable )
• Typically less expensive than down fill
• Allergic reactions are generally not an issue

• It is bulkier than down which could be an important factor for those backpacking.
• A sleeping bag using synthetic fill and with the same temperature rating as a down fill bag will be heavier. Again this could be important for those backpacking.
• The filaments gradually degrade overtime though development in fibre technology is improving this situation all the time.

CONSTRUCTION METHOD - the method used to keep the fill in place. It is no good having an efficient insulation material if it all ends up at one end of the sleeping bag.

The single layer construction: Stiched Through or Quilted method holds the filling in channels or baffles. However, you get cold spots along the stitch lines and therefore this method is unsuitable for cold weather bags.

ZIPS - as well as enabling easy access, zips can be used to control temperature in the sleeping bag- particularly those fitted with, '2-way' zips. On warm nights you can ventilate the bag from the bottom, this is very handy for bags with a high temperature rating.

Another aspect of zips to bear in mind is the baffle. Zips create a cold spot, so the baffle insulates it thus avoiding that cold shock sensation.

HOODS - Ever found you are all snug inside your sleeping bag but the top of your head does not feel quite as confortable - a sleeping bag fitted with a hood will come to your rescue. Many can be adjusted with the use of a simple drawcord.

NECK BAFFLES - the purpose of the neck baffle is to prevent the air your body has already made warm escaping. If this happens cold air drafts in particularly down the back of the neck. Typically they are adjusted by the use of a drawcord.

THE OVERALL SHAPE - essentially bags can be grouped into two shapes - the mummy shaped bags or rectangular bags

• Mummy Shaped Sleeping Bags - because these bags stay closer to your body and therefore have less air-space between you and the bag they are more thermally efficient. Additionally they tend to be a bit lighter because there is less material.
• Rectangular Sleeping Bags - though less thermally efficient, for those people that like more leg room they can provide greater comfort because they cater for more sleeping positions.