Epigenetics and light at night🚨

🪶 There's a new carcinogen on the block.

The U.S. National Toxicology Program (NTP) finished an interesting investigation this year. The title of the report is Night Shift Work and Light at Night and Cancer.

The purpose was to determine if night shift work and light at night (LAN) cause cancer. They have been kicking around the idea since 2007.

Night Shift Work and Light at Night and Cancer

Here is the final conclusion, 14 years later:

There is high confidence for a causal relationship between human cancer (breast and less so prostate) and persistent night shift work — i.e., frequent and long-term night shift work, especially beginning in early adulthood — that causes circadian disruption.

Furthermore:

There is moderate confidence for a causal relationship between human cancer and certain lighting conditions — i.e., excessive LAN exposure combined with insufficient daylight exposure — that cause circadian disruption. This conclusion is based on strong evidence that LAN acts through mechanisms that are likely to cause cancer in humans.

Based on this info, shift work and electric light at night (LAN) will be in the next the Report on Carcinogens (RoC).

Here's the link: Night Shift Work and Light at Night and Cancer (2021)

Night-shift Work and Epiginetics

If you have time, there is an older paper about cancer that I have been meaning to share for a while. This one is from an epigeneticist's viewpoint.

When I first came across it, I had to look up epigenetics. Here's the definition from the U.S. Library of Medicine in case you need a refresher, too:

Epigenetics is the study of how cells control gene activity without changing the DNA sequence.

It's easier to remember if you know that "epi" in Greek means on or above. So epigenetic means beyond the genetic code. This means the genotype stays the same, but the way it acts can be completely different. These changes can fluctuate daily, or last through generations!

I enjoy reading epigenetics, because these scientists always seem hopeful and proactive.

For example, here is their tidy conclusion after reading the cancer research:

These findings suggest that organizing our lifestyle according to environmental cues and daily biological rhythms can be a preventive factor that opposes cancer.

Salavaty, A. (2015)

Read the cancer review here: Carcinogenic effects of circadian disruption — an epigenetic viewpoint (2015)

Metabolic Disorders and Epigenetics

Here's another quote that I love from an epigenetic standpoint. This one comes from a review on obesity and other metabolic disorders:

Taking into account that genetics is behind [chronodisruption], as has already been demonstrated in twins’ models, the question is: Are we predestinated? We will see along these lines that nutrigenetics and epigenetics answer: ‘No, we are not predestinated’. Through nutrigenetics we know that our behaviours may interact with our genes and may decrease the deleterious effect of one specific risk variant. From epigenetics the message is even more positive: it is demonstrated that by changing our behaviours we can change our genome. Herein, we propose modifying ‘what, how, and when we eat’ as an effective tool to decrease our genetic risk, and as a consequence to diminish [chronodisruption] and decrease obesity. This is a novel and very promising area in obesity prevention and treatment.

Read the obesity review this came from here: Circadian rhythms, food timing, and obesity (2016)

The enthusiasm of the message is clear: there is another side to the story that "the modern lifestyle leads to modern disease." There is also the story that we can make informed decisions that change our lifestyle for the better!

Epigenetics and Future Generations

Through epigenetics, these changes can also live on in our children if they keep the same good habits. This why I see so many inspired people working so hard to build culture and community around this wisdom. It's not just about individual health. It's about the future wellbeing of humans and our place in nature.

That's all for today’s research post, but you can always catch up on past editions in the archive. Be sure to sign up for updates if you haven’t already!