the answer is that "it depends". Fire burns QI. Depending on the QI map of your home, having fire in the right location can enhance beneficial QI (or energy). It is ok to have a fireplace in your bedroom, just be aware that on the flipside you may unknowingly burn good QI or even encourage something undesirable. It should be safe, however, to be conservative with the amount of time that you use it. Pay attention to see what you experience. Of course, the best and recommended course of action is to seek a professional Classical Feng Shui reading to be sure. When in doubt, be a little conservative.