Light at night—high powered light bulbs that lead to so-called environmental light pollution—appears to lead to higher cancer rates, according to a study the University of Haifa.
According to researchers at the university, too much light at night leads to higher rates of prostate and breast cancer. The problem: Excess light screws up the creation of melatonin, a hormone released from the pineal gland during the dark. Cut out the melatonin and the risk of cancer rises.
The findings, led by Prof. Abraham Haim, built on earlier findings from the university where light at night (LAN) was linked to cancer.
In the latest study, Haim and a group of researchers set out to test the LAN-cancer link.
Four groups of lab mice injected with cancerous cells were examined: one group was exposed to “long days” of 16 hours of light and 8 hours of darkness, simulating exposure to artificial light beyond the natural number of light hours in a day; a second group was exposed to the same “long days” but were treated with melatonin; a third group was exposed to “short days” of 8 light hours and 16 dark hours; and a fourth group was exposed to the same “short days” but during the dark hours was exposed to a half-hour interval of light.
The results showed that mice exposed to short days (more darkness) had the smallest cancer growth. Mice exposed to LAN had larger growths and long days produced even larger tumors. The study also confirmed the melatonin link to LAN and cancer.
However, it’s not clear to researchers what mechanism triggers the LAN-cancer link. One thing is certain: Light pollution is a problem and disrupting biological clocks can lead to health problems.
