The Swanwick Classic Day Swannies are designed to be worn at any time during daytime hours, morning or afternoon. They block the segment of blue light that is suspected to cause problems for people viewing digital devices or sitting under artificial light, while still allowing in some of the segment of blue light that is thought to be beneficial during the day.
You may also want to wear blue light glasses at night, before bed, too. But, the Classic Day Swannies aren't ideal for nighttime wear. Blue light blocking glasses with dark orange lenses are better for just before sleep, as these block a wider segment of the blue light portion of the spectrum that may otherwise keep people alert.