Melatonin is the hormone (messenger molecule), that tells the body to go to sleep. In a normal person, melatonin naturally increases early in the evening after the sun has set. After a few hours, a person usually feels tired and goes to sleep. Melatonin goes from under 10 pg/mL to around 60 pg/mL late at night for an individual in their 20's. Melatonin levels naturally go down as you age, meaning this peak in melatonin will be lower the more seasoned you are.
Blue light exposure at night has been shown to reduce melatonin production by 40-60% in adults and even more in teenagers. This effect has been shown for extended periods (2+ hours) to as few as 10 minutes! This can disrupt sleep, and can even lead to insomnia. Blue Light Blocking Glasses have been shown to NEARLY ERASE this melatonin reduction in several studies conducted over the last 2 decades. This will result in better sleep, and overall health!