This doesn't have a timer on it however, this item isn't used right before or as you fall asleep. Blue light therapy consists of exposing your eyes to a sufficient quantity
of blue light for 30 – 60 minutes, 2–3 hours prior
to falling asleep or for the same duration in the morning. Blue Light has been shown to act as a “switch” to help regulate both sleep and daytime circadian rhythm.

The blue light signals the body to stop the production of Melatonin, this allows you to be more alert into the evening hours, and experience a more restful sleep when the body does produce Melatonin later in the sleep cycle.

This item should help you sleep soundly throughout the night. Blue light therapy consists of exposing your eyes to a sufficient quantity
of blue light for 30 – 60 minutes, 2–3 hours prior
to falling asleep or for the same duration in the morning. Blue Light has been shown to act as a “switch” to help regulate both sleep and daytime circadian rhythm.

The blue light signals the body to stop the production of Melatonin, this allows you to be more alert into the evening hours, and experience a more restful sleep when the body does produce Melatonin later in the sleep cycle.

This is the manufacturer's statement on this item: Researchers have found limited evidence that bright and blue light therapy may cause additional harm to people with pre-existing eye damage (including glaucoma and macular degeneration), and could increase the incidence of age related blindness. Medical professionals recommend people with pre-existing retinal conditions be tested prior to using any bright or blue light therapy system.