When the days turn cold, it’s natural to turn the heating up. However, what many people don’t realise is that many common bedroom mistakes could be undoing their efforts to keep their bedroom warm. For example, did you know that certain bed bases leak heat? Or that you shouldn’t sleep in cotton sheets at night? Below, Martin Seeley, the CEO at MattressNextDay, has shared seven surprising bedroom mistakes that could be making your bedroom colder and costing you more on your energy bill.