The Light at Night or LAN phenomenon and especially light in the blue wavelength spectrum have created a significant shift in human life since the industrial revolution.
Though it allows us to ‘wind up’ and keep working after dark, it also means this light affects our sleep-wake cycle in a significant way.
LED and fluorescent bulbs emit even more blue light than the older incandescent types from a few decades ago. UV light and especially light in the blue wavelengths affects our circadian rhythms, or daily ‘biological clock’ and special genes called clock genes that control our physiology (for example, hormone levels, inflammation) and even our behavior to a considerable extent.
This is a new frontier in medicine, much like our endocannabinoid system or ECS, another system we didn’t know about until a few decades ago. Unfortunately, too much LAN and especially blue light after sunset disrupts this all-important rhythm and has been linked in research studies to problems ranging from depression, chronic fatigue, susceptibility to infections and immune system problems, early dementia, and premature aging to obesity, certain cancers, and even diabetes.
Clock genes also help regulate the stress hormone response and cortisol levels, which can peak at the wrong time of the day – such as at night when you are trying to drift off to sleep leading to problems falling asleep or light fragmented sleep. Our clock genes may even influence our microbiome and contribute to the leaky gut and leaky brain hypothesis.