An organic cotton comforter is made from an organic cotton cover with organic carded cotton fill.
Carding is the process where cotton bales are strung out in lengths, ready to then be used to create clothing or bedding fabrics.
Carded cotton is either used as fill in mattresses, pillows and comforters or it goes through a finishing process to become fabric.
The fabric is then used for the cover.
You can sleep with an organic cotton comforter during any season. However cotton tends towards being more suited to summer. So if you live in an area with extremely cold winters or you really feel the cold you should either use an additional warm blanket or save the cotton comforter for summer and use a woollen one in winter. Yet if your winters are mild or you are a hardy soul cotton will be ideal for you all year round.
Cotton breathes well and is an effective insulator, meaning it will keep you cool when it is warm and warm when it is cool. It isn't quite as good as wool in this regard, although many people feel cotton is superior in comfort to wool. In the end your choice of comforter material will come down to personal preference. If you don't like wool for whatever reason cotton would be ideal for you.
Regular cotton has one of the heaviest uses of chemicals during production in the world. Not only is the plant grown using herbicides and pesticides but it is cleaned and processed with harmful toxic chemicals.
For cotton to be classed as organic it first must be grown on a field that has been free of artifical fertilizers, sprays and chemicals for three years. Weeding is done by hand and pests are controlled through natural methods. Organic farmers bring in good bugs to eat the bad bugs. It's harder and they have to be innovative, but the result is a healthy product.
Organic cotton is does not have the bright white finish of regular cotton because it isn't bleached with chlorine. It isn't as attractive, the color generally being closer to beige than white, but with an organic product you know you won't be breathing in harmful chemicals while you sleep.
The top of a comforter spends most of its time near your nose. You don't want to be snuggling into and breathing in all the toxins of a synthetic material, or even a natural material with added chemicals. Only a 100% organic product will suffice.