Health Risks Associated With Night Time Light

The advent of technology allows day-like lighting, while the use of entertainment gadgets like television and computers leads to delayed sleep. There have been studies conducted on identifying the ill effects of working during the night, affecting the circadian rhythm. However, a research team from Ohio State University studied the health effects of light exposure during the night. The damaging effects of our extremely illuminated lights, not only affect an individual’s health, but can also affect the offspring, according to the study. The study was published in the journal Scientific Reports. The study found that hamsters, when not exposed to natural sunlight during the day and darkness during the night gave rise to pups that had an impaired endocrine activity, as well as a weakened immune system.

The lead author of the study, Yasmine Cisse said that the findings of the study suggest that disruptions in the circadian rhythm have long-reaching effects on the offspring, which is a cause of concern. There have been numerous health problems like diabetes and cancer, associated with light exposure during the night, like the use of phones, TV, tablets and computers.

Senior study author, Dr. Randy Nelson, a professor and chair of neuroscience at Ohio State’s Wexner Medical Center, said that the health effects were now found to affect the offspring, the first study of this kind.

Health Risk of Night Time Exposure

Studies that were conducted earlier showed that there was a disruption of the endocrine function in adult mice which lead to behavioral and physiological changes in the offspring. The current study was designed to understand if the damage caused due to night time light exposure was passed on to the next generation.

Exposure to Light

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In the study, for 9 weeks male and female adult hamsters were subjected to

• normal light during the day and a dark night cycle
• or to low light during the night

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After the exposure to the differing routines, the hamsters were mated in one of the following ways:

• Female hamster exposed to dim light at night
• Male hamster exposed to dim light at night
• Both male and female exposed to dim light at night
• Both male and female exposed to normal exposure to light during the day and darkness during the night

The hamsters were placed under normal conditions, light during the day and darkness during the night. The offspring of these hamsters were also placed under normal conditions. The scientists carried out tests on the offspring to determine if they showed any signs of changes.

The findings of the study were

• Genetic alterations that occurred due to exposure to light during the night were passed on to the offspring
• Mothers and fathers independently transferred genetic alterations to their offspring.
• The offspring showed reduced endocrine activity as well as an impaired immune response
• Certain changes in traits were noticed only among female offspring, while certain others were seen only in male offspring.
• There was lowered immunity when exposed to foreign substances in the offspring of parents exposed to dim light at night.
• There were changes in the genetic activity in the spleen of the offspring

Normally, genetic alterations that occur in the female are believed to be transferred to the offspring, however, it was found that both male and female hamsters were found to transmit genetic alterations to the offspring. Dr. Nelson said that these genetic changes did not occur during pregnancy but they were inherited separately from the male and the female.

The study highlights the importance of adequate rest during the night and the ill effects of tampering with the sleep/wake cycle with the focus on an association between dim light and night time sleep.

Importance of a Light Free Night:

It is important to keep nights dark, as the scientists had carried out their work on Siberian hamsters which were nocturnal. The crux of the research is that nights should be maintained dark.

There is an increasing need to treat night time light as light pollution, as it leads to health hazards which can be far reaching. Previous studies have shown that it can lead to depression, cardiovascular disease, diabetes as well as anxiety disorders. The changing lifestyle has resulted in a lot of people watching TV late into the night or children playing with their tablets at bed time.

Night Shift Workers

In a study conducted by J M Harrington titled “Health effects of shift work and extended hours of work” and published in the journal British Medical Journals, the effect of working during the night and sleeping during the day was highlighted. The following effects were recorded

• Inability to sleep well during the day
• Drop in performance levels
• Mood disorders
• Cardiovascular disease risk
• Disruption in menstrual cycle
• Gastro-intestinal symptoms like flatulence, heart burn and abdominal pain
• Poor attention span could increase the risk for accidents

Such studies highlight the need for a good sleep environment, in the absence of light. Poor sleeping patterns and the use of tablets and other devices during the night can lead to genetic alterations which affect the offspring. The risk to the progeny should be a wake-up call for people who continue to be exposed to dim light during the night.



Source-Medindia