So you have a proper pair of hiking boots and now you will need a good sleeping bag. For some, choosing a sleeping bag may seem like quite a mission, down vs synthetic fill, mummy vs square and then there is the temperature ratings as well.
No matter what your choice of sleeping bag is, it will most probably be the most bulky item in your back pack. One thing to remember is that your sleeping bag together with your sleeping pad or mat forms an integrated sleeping system. You can have the best sleeping bag and still be cold if you don’t have proper insulation from the cold ground.
Before making a decision on what sleeping bag to get consider the following:
Temperature rating: It is better to get a sleeping bag rated a bit lower than the typical lowest temperature you think you might encounter. Rather be too warm than to cold.
Sleep system: How comfortable you will be at the lowest temp also depends on many other variables, and this includes the R-value of your sleeping pad. Your sleeping pad is the main barrier between you and the ground.
The type of insulation: There are mainly two types, down or synthetic. Each has its pros and cons, I will explain later.
Weight: Here the quality of the bags fill and the shape or cut will be the biggest factors that determine the weight. When comparing the weight of bags make sure you are comparing bags with the same temperature rating.
Features: Look at the extras that make the bag work better for you, adjustability, stash pockets and compatibility with sleeping pads.

What to look for: For the Drakensberg a 3 season sleeping bag will be suitable for most trips. Down is highly compressible and provides more warmth for weight than synthetic fills, however down is not best suited for wet conditions. Look for zipper baffles, draft collar and a snug fit for maximum heat retention. Look at a darker colour outer shell as this will also speed up the drying of any condensation.
Some considerations: If you are a cold or warm sleeper, you can adjust the temperature ratings up or down to suit you sleeping style similarly if your hiking trip is going to expose you to hot summer or to freezing winter trempratures.
Some sleeping bag manufacturers produce sleeping bags tailored to suite woman and its worth looking into.

Sleeping styles:
The thrasher – Look for a bag with elastic seams that can stretch, semi rectangular or a bigger girth for more room to move in.
The snuggler – look for bags that can be zipped together – this will allow you to get cosy with your significant other.
The perspire – look for a fleece lining or use a bag liner, synthetic fill with breathable shell and two way zipper for extra ventilation.
The polar bear – Look for synthetic linings, zipper baffles and draft collar, down fill bag liner and a contoured hood.

Temperature Ratings.
This should only be taken as a guide as there are a number of factors that will and can influence the temperature ratings of a sleeping bag. The use of a sleeping pad, sleeping indoors or outdoors, wet or dry and the season, will all play a role in how comfortable and warm you will feel.
1 Season – Best suited for summer or sleeping indoors, +15°C. A synthetic fill of 100g/m2 or a down fill of minimum 100g/m2. Have a brushed cotton or fleece lining for a non-stick comfort feel, no need for hood or draft collars with a wraparound zipper to open up fully for the use of a duvet.
2 Season – Best suited for summer sleeping in caves, tents or mountain hut, +15°C to +5°C. A synthetic fill of 200g/m2 or down fill of minimum 155g/m2. A cotton lining, fleece lining or cotton inner sheet, will help in warmer temperatures with the non-stick feel, no need for a hood or draft collars but could be nice in colder temperatures. A full length zip enables it to be used like a duvet.
3 Season – Best suited for autumn and early spring or in wetter climates – suited for most camping in the Drakensberg except escarpment use in winter, +5°C to -5°C. Look for a synthetic fill of 270g/m2 or down of minimum 250 to 280 g/m2. A synthetic liner to reduce weight or inner sheet (an inner sheet will help keep a down bag clean), breathable but water resistant shell for wetter weather, draft tubes and collar nice to have and a slimmer more mummy shape to help keep warm air in and reduce weight.
4 Season – Best suited for winter camping on the escarpment of the Drakensberg, -5°C to -15°C. Look for a synthetic fill of 300g/m2 or super down fill of minimum 280 g/m2. Synthetic liner with breathable outer and DWR finish – use of a fleece sleeping bag liner will add a few degrees of warmth and will help keep it clean. An adjustable draft collar and contoured hood with a bigger girth for extra layers is a good idea and a mummy style to help retain heat and keep weight down.
5 Season – Best suited for high mountain or arctic use, -15°C to -25°C or lower. Look for a down fill of no less than 310g/m2. It will have all the features of a 4 season bag but might be a bit roomier to accommodate extra layers and be a bit longer to help with storing of water bottles and temperature sensitive equipment.
There is a lot of information on the internet in regards to sleeping bags and I have only touched on a few points. REI has a good section on sleeping bags with good information and explanations;

The sleeping areas in Spare Rib Cave