In fact, your bedroom is not a public place, and therefore mustn't be furnished in a strict manner. You should feel entirely free to decorate your wall and add furniture to this place however you desire it. There are no rules or obligations for you.
The truth that the average person spends around 7 to 9 hours in his or her bedroom makes it crystal clear that this place has to be valuable for you. If you cannot sleep well at night because you don't feel comfortable or safe in your bedroom you are very likely not going to produce optimal results in your profession. At the same time, it should be clear that having interrupted sleep can damage your health enormously. The better you can sleep at night the better results you will produce out there in the world.
