Thomas Edison should shoulder some of the blame for the potentially frightening health risks facing 11 million workers: those who work the graveyard shift.

Research is showing that creatures of the night — nurses, bakers, firefighters, transportation workers, third-shift employees, police officers and others — might encounter serious side effects from working when the sun doesn’t shine.

• International researchers, analyzing results of 34 studies, found that shift work was associated with a 23 percent increased risk of heart attack among more than 2 million night, evening and rotating-shift workers, the British Medical Journal reported. Among night-shift workers only, that number rose to 41 percent. Interestingly, shift work was not associated with increased death rates.

• Researchers at Brigham & Women’s Hospital Division of Sleep Medicine found that among workers with pre-diabetes conditions, the disease is more likely to develop in night workers than those who work days. Additionally, sleeping at “abnormal times” and not getting enough sleep leads to lower metabolism and higher spikes in blood sugar.

• Teens who work “off-hour employment” before age 20 may be at risk for multiple sclerosis due to changes in their sleep patterns and disruption of their circadian rhythms, according to the Karolinska Institutet in Stockholm.

That’s why Edison, the inventor of the light bulb, is “the person to blame, obviously,” according to Dr. David Luterman, medical director and director of the Baylor Sleep Center in Dallas.

“When it was dark, there was nothing to do but sleep,” Luterman says. “Then the light bulb came, and then Henry Ford puts in shifts all over the place. Then radio, which was entertainment in your own home. Then the TV.”

Which led, of course, to overnight jobs, to off-kilter sleep schedules and to health problems that go bump in the night.

Problems strike only some

While these shifts can lead to serious health issues, they’re not a given.

“It can mess up your life,” Luterman acknowledges. “But not everybody who does shift work is affected. About 20 percent have significant problems doing it. There’s no rhyme or reason who will or won’t.”

Every cell in our bodies, he says, has a biological rhythm. The brain has a master clock that trains us to be awake during the day and asleep at night. Thus, when light and dark are out of whack, so are we — if we’re not careful.

“Simply put, the human body is designed and wired to respond to diurnal cues that have to do with nature’s clock: daylight and nighttime,” says Gerry Jacob, CEO of Wellfirst Sleep Diagnostics, whose sleep centers evaluate and treat people with sleep issues.

Upending that by working at night or by alternating sleep and wake shifts can lead to dysfunction, Jacob says. For instance, it throws off production of melatonin, the hormone responsible for rest.

As far as causing obesity and other problems, Luterman says he is unsure of the correlation. There is one, he says, “but I don’t know the physiology of it.

“Hormones, insulin, things like that are secreted in diurnal variation,” Luterman says. “When you do shift work, you’re opposing some of your normal hormone stasis equilibrium.”

One problem is that people get their nights and days mixed up, he says.

“They work at night, but try to revert back to daytime on their days off. If you try to reverse, you’ll have a hard time doing it. You have to shift your sleep schedule.”

Shield yourself

Here are ways to lessen the chances that working nights will cause problems:

Regulate light and dark. When night-shifters get off work, the sunlight while they’re driving home stimulates them to stay awake, says Dr. David Luterman. “We tell people, ‘Wear dark sunglasses on your way home. Use blackout curtains so when you go into your house, it’s dark.’ ”

Keep it quiet. Tarah Grooms of Methodist Richardson Medical Center recommends wearing ear plugs or playing soft music. “There’s an app for the sound of rain. A lot of nurses use that.”

Sleep when you can. Just sleep. For some people, it may be right after they get off work. Others might want to wind down first.

Use rotating shifts to your advantage. If you have a choice, Luterman says, opt for a day-evening-night shift rotation over night-evening-day. “It’s easier to advance it than to reduce it, just like it’s easier to fly and adapt from Los Angeles to New York than New York back to L.A.”

Make sure your work area is well-lighted.

Adopt healthy practices. Regulate caffeine. To make sure you can sleep when you get off work, Grooms recommends no caffeine past midnight. Drink lots of water. And yes, that evergreen advice: Exercise.