Seventh Generation Natural Spectrum Light Bulbs provide a more balanced light by filtering out the excess yellow and green light emitted by ordinary bulbs. Natural spectrum light should help you to read for longer periods with less eyestrain. You should also experience a warmer and more pleasing, natural looking environment. Colors will look truer and more vibrant. Contrast will be sharper. Many people experience an improved mood, especially in winter when natural light can be scarce. They lasts 3,500 hours, four times longer than ordinary light bulbs and Saves energy (used to manufacture the bulbs).