Light At Night (Is Not Alright)

I think we all know that sleep is vital for health. It’s also critical for fat loss. There’s so much to say about it, but this newsletter will focus on just one aspect: light.

A report online in the Proceedings of the National Academy of Sciences stated that those with increased exposure to light at night (especially those that do shift work) are linked to higher rates of obesity.

They believe this increased exposure to light at night disrupts the release of melatonin, which is a hormone produced by the pineal gland in the brain (read more about it below).

Coauthor and Ohio State University professor of neuroscience and psychology, Randy Nelson, looked at the effects of nighttime light exposure in 8 week old male mice. The animals were exposed to two different 24-hour trials: a standard light-dark cycle which consisted of 16 hours of light and 8 hours of darkness AND 16 hours of light and 8 hours of dim light (to mimic those living in industrialized nations and to those that do shift work).

As early as one week after the testing began, there was a greater increase in body mass observed among the mice exposed to the dim light. Those exposed to the standard 8 hours of darkness did not experience this increase in body mass.

At 4 weeks, the dim light groups showed impaired glucose tolerance (not good for fat loss). Dr. Nelson states that they conducted another experiment where there was a light-dark cycle and a dim light cycle, but the mice had continuous access to food. The dim light group seemed to eat at night and ate more total calories compared to the dark cycle group. Although these experiments were done with mice, and not humans, mice are similar in regards to repeated behaviors.


The 2017 Nobel Prize in Physiology and Medicine has been won by Jeffrey C. Hall, Michael Rosbash, and Michael W. Young; three researchers who made discoveries in the molecular mechanisms controlling circadian rhythm.

That should tell you how important sleep quality and duration are to our health, especially on the human endocrine system. Sleep is the switch that triggers a cascade of hormonal production that is very far-reaching and yet fragile. 


Melatonin production is a very light-sensitive process and even a tiny amount of light can mess it up and impair your sleep. Your skin contains photoreceptors that detect light, if you are not sleeping in total darkness, your pineal gland will decrease the production of melatonin, the circadian rhythm regulating hormone, and your adrenals will start synthesizing cortisol (stress hormone).

notebook writing computer
Limit blue light exposure at night!

Take Action

  • No social media at least one hour before bed. (This is a big trigger for dopamine, which can inhibit relaxation needed to sleep).
  • Limit usage of electronic screens at night. (For Apple mobile devices, you can go to Settings > Display & Brightness > Night Shift to reduce disruptive blue light emission).
  • Don’t keep any electronics in your bedroom.
  • Use “black-out” curtains to restrict any ambient outside light.

Expect Success,


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