Cotton or linen bedding is cooler than a polyester mix and it allows the skin to breathe. Opt for natural sheets, 100% cotton sheets and duvet covers are more effective than synthetic alternatives. However, cotton may be lovely and cool, but it will stay damp if you sweat. There are some great products with technical fabrics available today which help with night sweats. Avoid memory foam as this retains heat. Choose light bedding, it is easier to have a light duvet and then add an extra layer which you can throw off when it gets too hot, like wool which is a highly effective natural fibre when it comes to absorbing moisture.
Have a look at my favourite pieces of clothing and some ideas on how to keep cool in the bedroom!