Happy Light is used for winter and or daylight savings time blahs . The Happy Light is commonly prescribed for SAD, or seasonal depression disorder. This is our Best selling day light therapy light/lamp made by Verilux. Liberty Model 5K. 5,000 Lux moderate UV light output. Compact, durable , perfect for office spaces, bedrooms, etc. Very portable unit. Weight 1.5 pounds, 6 x 7 x 3. Minimal assembly required. This unit has been tried and tested by owner . Works great but don’t use at night.