Treats SAD (Seasonal Affective Disorder) and winter blues or simply lifts mood and boosts concentration and energy levels High-contrast light with adjustable neck for reading and focused tasks, with touch-control brightening Recommended treatment time with soft light: 60 minutes. Removable diffuser brings treatment time down to 30 minutes Can be switched on all day, or make up your recommended session by dipping in throughout the day Certified Medical Device (class 2a), producing 10,000 lux at 22cm, 2500 lux at 50 cm, independently measured, 3 year guarantee