Weakened Immune System Passed on to Offspring
Artificial light in the night time has become a fact of life over the past century as electricity and screens have illuminated nights and extended waking hours. This illumination can be a good thing since light allows almost any activity to be done at any time, but it comes at the cost of sufficient sleep. Sleep is regulated in very large part by an internal body clock called the circadian rhythm, a cycle of bodily processes that repeats approximately every 24 hours. The cycle is mostly self-sustained, but it can be influenced by external factors like light or temperature. Unsurprisingly, circadian rhythms are also essential to a healthy immune system, meaning that someone whose bodily clock is not set correctly may be more vulnerable to sickness. Now, a recent study from Ohio State University has shown that this vulnerability can actually be passed down through generations, an effect known as transgenerational inheritance.
The study involved two groups of Siberian hamsters. One group was exposed to a nine week cycle with standard lighting conditions: bright during the day and dark during the night. At the same time, the other group underwent an equally long cycle with altered lighting conditions: bright during the day and dim at night. The light level was comparable to sitting a few feet away from a lone candle. After the light treatment, the groups were allowed to breed and all returned to standard lighting conditions.
The study involved two groups of Siberian hamsters. One group was exposed to a nine week cycle with standard lighting conditions: bright during the day and dark during the night. At the same time, the other group underwent an equally long cycle with altered lighting conditions: bright during the day and dim at night. The light level was comparable to sitting a few feet away from a lone candle. After the light treatment, the groups were allowed to breed and all returned to standard lighting conditions.
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Once the offspring had become adults, a series of different stimuli were used to test their immune systems. These tests showed that parental exposure to a dim light at night resulted in a weakened cell-mediated immune response in the offspring, though there was some evidence of a strengthened humoral immune response in a sex-specific manner. What this means is that paternal exposure to light at night slightly strengthened the humoral response in male offspring, and maternal exposure slightly strengthened it in female offspring. All groups that were exposed to light at night produced offspring with a decreased expression of melatonin, a hormone regulated by the circadian rhythm. Additionally, every group demonstrated that light exposure on the maternal side was more detrimental than on the paternal side, probably because mothers were kept with the offspring until weaning and could continue to affect the new immune system through nursing.
Plenty of past studies have demonstrated the link between sleep and the immune system, but this study is the first to show that physiological changes in immunity can be passed down through generations. The effects of this procedure on the human immune system are unknown, but hamsters and humans have very similar genetic characteristics, a feature suggesting that the results may generalize to many other mammals. This makes getting a good night’s rest essential not only to a healthy mind, body, and lifestyle but also to the well-being of future generations. If a single candle is enough to suppress immune responses across generations, one could only imagine the potential downfalls of endless night hours spent staring at a screen.
Plenty of past studies have demonstrated the link between sleep and the immune system, but this study is the first to show that physiological changes in immunity can be passed down through generations. The effects of this procedure on the human immune system are unknown, but hamsters and humans have very similar genetic characteristics, a feature suggesting that the results may generalize to many other mammals. This makes getting a good night’s rest essential not only to a healthy mind, body, and lifestyle but also to the well-being of future generations. If a single candle is enough to suppress immune responses across generations, one could only imagine the potential downfalls of endless night hours spent staring at a screen.
Featured Image Source: Unsplash
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