Your bedroom should be peaceful and quiet, so out with any loud colours, mess and halogen lamps! Go for pastel tones, dimmed lighting and space. If you have your desk in your bedroom, separate it off with a partition.
Keep a minimum of electrical equipment in your room, even if it's turned off: even the weak waves they emit can interfere with your brain (electromagnetic radiation).
Invest in good quality bed linen without quibbling over the price: it will last you a good ten years or more!