Light Pollution: An Unexpected Killer

by Lizzie Bennett

Numerous studies have shown that people who work night shifts over an extended period of time die sooner than their day-shift counterparts.

What is even more apparent from studies is that night workers have a much higher incidence of illness, especially heart disease and diabetes, than those working during the day.

Working the overnight shift may dramatically increase your risk for a heart attack, new research suggests.

Shift work is defined as employment outside of a traditional “9 to 5” daytime schedule, including regular evening or night shifts, rotating or split shifts that can vary in time depending on the day or week and other irregular work schedules.

For the new research, published online in the British Medical Journal, scientists analyzed results from 34 earlier studies involving more than 2 million people. Out of those, about 17,350 had some sort of heart event with 6,600 having a heart attack and 1,850 having an ischemic stroke, caused by lack of oxygen to the brain.

A closer look found such heart problems were more common in shift workers: They were 24 percent more likely to experience a coronary event, 23 percent more likely to have a heart attack and 5 percent more likely to suffer a stroke. The risk increases remained the same after ruling out the study participants’ unhealthy behaviors.

Night-shift workers were found to fare worst, with a 41 percent increase in risk of having a coronary event. Shift workers, however, were not more likely to die from any cause compared with their daytime-working counterparts.

Study author Dr. Daniel G. Hackman, assistant professor of medicine at the University of Western Ontario in Canada, told WebMD that while the studies he and his team reviewed were observational and only suggested an association between heart problems and shift work, “the relationship is probably causal.”

The study’s authors say their research could lead to more targeted screening programs to identify health risks in shift workers in addition to programs to educate workers on their risk.

“If you are a shift worker, know your cardiovascular risk factors cold,” Hackman said. “Go see your family doctor and get an annual physical. And ask for measurement of your blood pressure, waist circumference, cholesterol, triglycerides and fasting blood sugar.”

This isn’t the first study to find that shift workers face health risks from their varying schedules.

Recent research finds that shift workers may decrease their metabolism and experience spikes in blood sugar after eating, raising risks for diabetes and obesity. (source)

Or this from The Daily Mail:

Night shifts can raise the risk of heart attacks and strokes by more than 40%. Researchers analysed the results of 34 studies involving two million people.

Shift work can dramatically increase the risk of heart attacks and strokes, warn researchers.

A study of two million people found shift workers are almost 25 percent more likely to suffer.

Night shift workers run the highest risk of 41 per cent, says a study published on the British Medical Journal website bmj.com.

People working shifts also have higher levels of unhealthy behaviours such as eating junk food, sleeping badly and not exercising, which are linked to heart problems.

But researchers said they took this into account – and the excess risks remained. (Continue reading the article here.)

New research suggests that day workers are starting to suffer from similar ill-health to night workers, and they think the reason is light pollution.

Humans are naturally diurnal, active during daylight hours and resting during the night. Prior to the discovery of electricity many activities where limited once it got dark, people tended to go to bed earlier, and get up at first light. Electricity changed all that.

Electricity allowed the activities of the day to continue for as long as you wanted them to, but that was usually within the home. 24-hour shopping and television were unheard of, the local shop was not ablaze with neon and streetlights were far fewer than they are now.

Curtaining and drapes tended to be far heavier than they are now, where the tendency is to create light and airy spaces. The heavy drapery that covered our windows in times gone by kept out drafts…and light.

As we ‘progressed’ electricity took over our lives. Our bedrooms are now multi-functional spaces, used for working on the laptop for half an hour before lights out, to make calls on mobile phones or to Skype friends across the world on our tablet devices. We have televisions and digital clocks and light, thin curtains that fit with the current fashion. Add to this mix the constant flicker of car headlights, and stores that are illuminated through the night, and it wouldn’t be wrong to say we are never truly in the dark these days.

Our bedrooms, in the past, had three functions. They were used as a place to confine the sick, as a place to sleep and as a place to have sex.

Lack of quality sleep can lead to ill health, we know this, we insist on laying our babies in quiet dark nurseries, our children are told they have to go to bed early to grow big and strong, yet we ignore our own needs.

Bedrooms that are over illuminated promote bad sleeping habits. On an evolutionary level we are not yet at the point where we can blur the edges of day and night for more than a few hours without suffering for it.

Northern Alaska, and other areas that are above the Arctic Circle have periods of 24-hour light for months at a time, followed by months of darkness. There are a couple of studies looking into the effects of this on the human body, but the results are not in yet.

Inkirri, a nurse from Lapland tells me this:

Growing up with only two days in a year, both lasting six months made it seem normal to me! My parents made sure we had a routine from an early age. The whole house had thick drapes at the windows, and at about 5pm mother would close them and we would start to wind down from our day. We would do our homework and then eat dinner, then we could play for a while before starting the bedtime routine. As we got older the curtains got pulled a little later but the routine was maintained.

There were children whose parents were less strict, and you could tell who they were. They performed worse at school, and looked pale…even more pale skinned, than the rest of us.

You have to have a very positive attitude when you are living with such extremes, and it’s hard to have a positive attitude when you are tired and cranky.

There are of course treats that we experienced, a midnight BBQ, which was a yearly event was something we really looked forward to.

Most people coped well, like I say, we were born to it. Those that had problems had usually moved up from the south for some reason and they had terrible trouble sleeping until they built their routine.

Do yourself a favor, buy some decent curtains, watch TV in the lounge and leave your laptop in its bag…your body will thank you for it.

Contributed by Lizzie Bennett of Underground Medic. Lizzie Bennett retired from her job as a senior operating department practitioner in the UK earlier this year. Her field was trauma and accident and emergency and she has served on major catastrophe teams around the UK. Lizzie publishes Underground Medic on the topic of preparedness.