There are two basic types of light therapy: bright lights and dawn simulation. Bright lights deliver LOTS of light - hence the name! They provide you with a supplement of light on those days when nature doesn't deliver or when you're stuck indoors. Bright lights come in two forms. Light boxes are the best known bright light therapy product but, as an alternative, light visors are a convenient way of getting light therapy whilst you move around the house and mean you don't have to sit in one place as you do with a light box. All will help to boost your mood and energy levels.
Dawn simulation doesn't provide lots of light; it simply copies a natural sunrise by gradually increasing the light at your wake-up time which gives you a head start and helps you to feel better all day. Dawn simulators can be used in addition to bright lights for treating SAD or on their own for milder winter blues symptoms. They're especially good if you're just not a morning person and have trouble getting going!