Hi,

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…