Rotating Night Shift Work and Type 2 Diabetes in Women

A new study found that the longer women worked rotating night shifts, the greater their risk of developing type 2 diabetes. Researchers also found that extended years of rotating night shift work was associated with weight gain. The weight gain may have contributed to the increased risk of type 2 diabetes.

Women who worked rotating night shifts for three to nine years faced a 20 percent increased risk of type 2 diabetes. Women who worked nights for 10 to 19 years had a 40 percent rise in risk. And women who worked night shifts for over 20 years were 58 percent more at risk. Women who worked rotating night shifts also gained more weight and were more likely to become obese during the follow-up.

Rotating night shift work was defined as three or more night shifts plus day and evening hours each month. The Harvard School of Public Health tracked more than 175,000 U.S. nurses for this study. Findings were published Dec. 6 in the journal PLoS Medicine.

Researchers said the findings need to be confirmed in men and ethnic groups (96 percent of the nurses were white Caucasians). The U.S. Centers for Disease Control and Prevention (CDC) estimates that 15 million Americans work full time on evening shifts, night shifts, rotating shifts or other irregular schedules.

Read more about shift work sleep disorder and women’s sleep needs. More stories about sleep and type 2 diabetes are available on the Sleep Education Blog.

Photo by DIAC Images

Second Air Traffic Controller Sleeps through Midnight Shift

For the second time in two months, an air traffic controller was caught sleeping on the job. A Federal Aviation Administration report says the unnamed controller didn’t accidently doze off - he intentionally slept for five hours.

The incident happened at McGee Tyson Airport in Knoxville, Tenn. on February 19 – more than a month before a supervisor working alone at Washington’s Reagan National Airport unintentionally fell asleep for nearly a half-hour.

Unlike the incident a month ago, the Knoxville controller is being fired by the government for “unprofessional and inappropriate behavior.”

It’s easy to blame an irresponsible employee, but as the Sleep Education Blog reported recently, the problem runs much deeper.

Air traffic controllers face notoriously difficult sleep schedules. One common schedule for air traffic controllers known as the “rattler” involves returning to work a midnight shift only hours after working a daytime shift. The nickname “rattler” comes from the damage the shift does to sleep patterns.

The problem of fatigued air traffic controllers are hardly a new one. In 2007, the National Transportation Safety Board released a report that shed light on how sleep deprivation affects job performance. The report revealed that air traffic controllers get an average of only 2.3 hours of sleep before a midnight shift. Rapidly rotating shifts and short rest periods between shifts lead workers to be fatigued before a shift even begins.

To make things worse, most midnight-shift air traffic controllers work alone. The National Air Traffic Controllers Association emphasizes staffing problems as the cause for both cases, and is demanding there be extra controllers during overnight shifts as safety measure.

The FAA is hesitant to hire, because air traffic controllers generally earn high pay and have pricey benefits. The U.S. Labor Department Bureau of Statistics reports that the average salary of air traffic controllers was $109,218 in March 2009. Transportation officials may have a difficult time justifying that kind of cost in the current political and budgetary climate on Capitol Hill.

It’s possible that air traffic controllers will see some type of regulation that affects their schedules as a reaction to both incidents. In the meantime, the AASM has provided air traffic controllers and shift workers with a list of tips that can help with the midnight shift.

Shift Work May Cause Swell in Sleep Apnea Symptoms

A new study provides further health concerns for the estimated 20 million Americans who sleep during the daytime because of their work schedule. The symptoms of untreated obstructive sleep apnea may be worse for shift workers, a new study reports.

The study compared a group of 31 shift workers to ten daytime workers. Members in both groups were previously diagnosed with sleep apnea and had similar ages, weights and sleep lengths.

Daytime and nighttime polysomnograph results show that the shift workers had more frequent breathing pauses in breathing and higher oxygen desaturation levels. Both measures show that shift workers had more severe symptoms of sleep apnea.

The authors of the study caution that patients with untreated sleep apnea should avoid nighttime work. The Sleep Education Blog urges workers with sleep apnea to take that warning one step further and never let sleep apnea go untreated. Sleep apnea has been linked to heart disease, diabetes, dementia and other serious health problems.

Shift work also can also harm your health. Some workers may struggle with shift work disorder, which causes your internal body clock to go awry. Workers with shift work disorder may be severely tired but unable to sleep. Loss of sleep length and quality may affect job performance and put workers at risk for injury.

Read more about obstructive sleep apnea and shift work disorder.

Late-starting shifts harm sleep, limit productivity

The key to maximizing workplace productivity while minimizing fatigue may be a shift start time that allows workers to sleep right before reporting for duty.

New research suggests shifts that start in the late morning to early afternoon work best for employees. Start times between 8 p.m. and 12 a.m. may limit sleep and harm performance.

Sleep can be difficult to come by during the late night shifts because the timing conflicts with the body’s early evening circadian process.

According to the findings employers would benefit by rescheduling shift starting times to maximize employee alertness and sleep. Lead investigator Angela Bowen suggests a change in public policy may be necessary. Government regulations that limit the number of hours worked would also include provisions for shift start times.

“Shifts of equal duration differ in how fatiguing they are depending on the time of day when they are scheduled,” said Bowen. “The same limitation on the number of duty hours may be either overly restrictive if during the day or too liberal if during the night.”

The study used a mathematical formula based on a sleep regulation model that predicts the effects of sleep and wake times on sleep quality and waking fatigue. The researchers used the formula to see the effects of 24 start times, each varying by one-hour increments. The hypothetical work schedule lasted six days. Each shift was nine hours and started at the same time each day.

For those with no choice but to start their shifts during the undesirable late evening hours, the key is to find a sleep schedule that works. Past studies have suggested overnight workers go to sleep in the late morning hours immediately after work and wake up before the start of the early evening peak. On days off, it’s desirable to provide a compromise, by going to sleep at about 3 a.m.

Learn which professions are the worst for sleep.

Image by Shawn McClung

Study: Caffeine beneficial for shift workers

If you work overnights, drinking a cup of coffee early in your shift might not be a bad idea, new research suggests.

A review of several studies published in the May issue of the Cochrane Database of Systematic Reviews found caffeine appears to help cut down mistakes on the job for shift or nighttime workers.

Researchers analyzed the findings of 13 studies examining the effects of caffeine on workers

Most of the studies took place at simulated workplaces inside sleep laboratories. Subjects took caffeine in the form of coffee, energy drinks, pills and caffeinated foods.

Compared to placebos, caffeine was associated with better overall cognitive performance.

Shift workers who took caffeine made fewer errors than those who took naps.

The review was not able to pin down if caffeine could reduce the frequency of work injuries because of a noticeable gap in previous research.

The authors are cautiously supportive of using caffeine to get through shift work.

Past studies have shown caffeine can negatively impact daytime sleep. However AASM task force found your sleep is unlikely to be disrupted if you consume caffeine more than 8 hours before bedtime.

Combining caffeine at the start of an overnight shift with an evening nap may be your best option. A 2006 study found that can improve job performance and reduce sleepiness.

Image Courtesy Ladik

Sleep problems often persist after shift work, not permanent

There’s some hope for folks ready to give up the struggle with the overnight shift: insomnia and other sleep problems often associated with those difficult hours may be difficult to shake when it’s over, but it’s not permanent.

Research also shows more years of shift work does not lead to worse sleep problems.

These findings were part of a 10 year longitudinal study in the April issue of Journal of Occupational and Environmental Medicine. Researchers followed workers in their 30s, 40s, 50s, and 60s over various lengths of time.

Former shift workers had more sleep-related problems than those still on the graveyard shift or people who worked normal hours. Researchers reason this group is “self-selected,” meaning they were predisposed to have sleep disorders, and their difficulties persisted after they left their jobs.

Those who were still in early in their professional lives had the most problems. They were most likely to leave their jobs.

Shift workers also had more problems sleeping than daytime workers, often waking up too early.

For more on the night shift, go here to find a sleep schedule that works, or go to Sleepeducation.com to learn everything you need to know.

Caffeine & the Night Shift

A recent study examined the effect that consuming caffeine at night may have on daytime sleep.

The sleep of participants was monitored during a night in a sleep lab. Then they stayed awake in the lab for 25 hours. While awake they were given caffeine capsules. Then their sleep was monitored again as they slept during the day.

Results show that daytime sleep was worse after taking caffeine. Measures such as sleep efficiency and sleep duration were lower.

So does this mean that people who work the night shift should avoid caffeine? Not necessarily.

The participants were given caffeine late during the night. They took a 100-mg dose three hours before attempting to sleep during the day; they were given another 100-mg dose only one hour before daytime sleep.

The stimulating effect of caffeine can last for hours. So it’s no surprise that their sleep was affected.

But an AASM task force report concluded that your sleep is unlikely to be disrupted if you take caffeine at least eight hours earlier. And other studies show that caffeine helps improve the performance and alertness of night-shift workers.

A study in the journal Sleep in 2006 found that combining caffeine with an evening nap provided the greatest benefit. Before a simulated night shift, participants were given a nap opportunity at 7:30 p.m. Their average nap duration ranged from 73 to 99 minutes.

At about 10:30 p.m. they were given 4 mg/kg of caffeine. The authors reported that this dose has been shown to be effective without interfering with daytime sleep.

A 4 mg/kg dose means that you take 4 mg of caffeine for each kg of body weight. So the dose would be about 272 mg if you weigh 150 pounds, 318 mg if you weigh 175 pounds, and 363 mg if you weigh 200 pounds.

A second part of the study involved actual night-shift workers who took 300 mg of caffeine at the start of each night shift. It also found that caffeine and napping improved performance and reduced sleepiness.

On Tuesday the Sleep Education Blog reported that another option for night-shift workers is to follow a “compromise” sleep schedule.

Read about sleep & caffeine on SleepEducation.com to find out how much caffeine is in your coffee, soda or tea. Learn about shift work sleep disorder.

A Sleep Schedule that Works for the Night Shift

A series of studies have found that a “compromise” sleep schedule is effective for people who work night shifts. The results of the latest study were published in the Nov. 1 issue of the journal Sleep.

The sleep schedule improves alertness during the night shift and daytime sleep after the shift. But it also provides a “compromise” that helps night-shift workers on days off.

It enables them to get the sleep they need; but it also gives them more free time during the day.

“We think that most real shift workers want to be awake on their days off,” lead author Mark Smith, PhD, previously told the AASM.

Here’s the “compromise” sleep schedule for night-shift workers:

• Sleep from 8:30 a.m. to 3:30 p.m. after regular night shifts.


• Sleep from 8:30 a.m. to 1:30 p.m. after the last night shift before a weekend off.


• Sleep from 3 a.m. to noon on days off.

The studies also used three light-related strategies to increase the effectiveness of this schedule. Light is an important timing cue that helps your body regulate sleep and alertness.

First, workers received bright light therapy during simulated 11 p.m. to 7 a.m. night shifts. Light boxes were used during four, 15-minute sessions.

The first session began at 12:45 a.m. These sessions were repeated hourly, with the final session ending at 4 a.m.

Second, workers had to go outside within the first two hours after waking up. They needed to get at least 15 minutes of exposure to daylight.

Third, the workers wore dark sunglasses at all times when outside during the day. This was most important when traveling home after a night shift.

The current study found that workers had improved mood, fatigue and performance during night shifts when following the compromise sleep schedule. These levels were similar to daytime measurements obtained during “9 to 5” work days.

The authors caution that the participants were not real shift workers; they were young volunteers. The “night shifts” were conducted in a laboratory. So the compromise sleep schedule still needs to be tested in real night-shift workers.

Learn about shift work sleep disorder on SleepEducation.com.

Image by GaijinSeb

Women, Shift Work and Breast Cancer

BBC News reports that some women in Denmark who developed breast cancer after years of working night shifts are receiving compensation from the government.

Is there a clear link between shift work and breast cancer?

A 2008 review found only limited evidence. Yet there was enough data to convince the International Agency for Research on Cancer.

The IARC convened a working group in 2007. It was composed of 24 scientists from 10 countries. The experts reviewed all of the research.

They concluded that working night shifts is “probably carcinogenic to humans.” This means that shift work may be a factor “that can increase the risk of human cancer.”

The report was the basis for the Danish government’s compensation program. So far almost 40 women have received payment through the program.

How might night shifts promote breast cancer?

The exact mechanism is unclear. But it may be related to how shift work disrupts the “circadian rhythms” that are controlled by the body clock in your brain. This internal timing system regulates the daily cycle of various body functions.

It controls your body temperature and hormone levels. It also regulates your alertness.

One way the body promotes sleepiness is by producing more melatonin at night. This acts as a “sleep signal” for your body.

But light exposure during night shifts suppresses melatonin production and disrupts your sleep/wake cycle. These disruptions may promote the growth of cancerous tumors.

Get sleep tips for shift workers from the AASM.

Drowsy Driving & Rumble Strips

You’re sleepy, but you’re intent on making it to your destination on time. So you keep driving.

You fight to keep your eyes open. Suddenly you’re startled by a loud noise as your car begins to shake.

Your eyes pop open as you realize that your car was drifting off the road. You just encountered a rumble strip.

The first shoulder rumble strips appeared on New Jersey's Garden State Parkway in 1955. They are used to prevent run-off-road crashes.

The Federal Highway Administration reports that this type of crash causes one-third of all traffic fatalities. The main cause? Drivers are too sleepy.

But are rumble strips an effective solution for drowsy driving? A recent study examined how rumble strips affect sleepy drivers.

Thirty-five shift workers operated a driving simulator in the morning after a full night shift. Measures of sleepiness such as eye closure duration increased as they drove.

After hitting a rumble strip their alertness increased in most parameters. But the alerting effect was very brief. Signs of sleepiness returned after five minutes.

So a rumble strip may briefly wake you up. But it won’t keep you from drowsy driving.

What should you do if you feel drowsy when you’re behind the wheel? Let another passenger take over the driving duties.

Or pull off the road at a rest stop. Have a drink that contains caffeine and then take a brief nap. Put your alertness – and your safety – first.

Sleeping on the Job Proves Costly

ABC News reports that a nuclear power plant was fined $65,000 because security workers were caught sleeping on the job.

Video images of sleeping guards were recorded by a fellow guard at different times of day. A federal investigator also discovered a guard sleeping at his post.

The incidents occurred at the Peach Bottom Nuclear Plant just outside of Philadelphia. The guards are responsible for protecting the plant from a terrorist attack.

Falling asleep on the job is a clear sign of severe sleep deprivation. This is common when security guards work more than one job.

Excessive daytime sleepiness can be a sign of another sleep disorder. These include obstructive sleep apnea, restless legs syndrome and narcolepsy.

Sleepiness on the job also is a common sign of shift work disorder. The problem can be severe for people who work rotating shifts or night shifts. This forces them to be alert at a time when the body is normally asleep.

Then they have to try to sleep during the day. Daytime distractions can make this difficult. In a recent study of 163 nurses, more than 70 percent of the nurses report that they are unable to get enough sleep.

A recent study in the journal Sleep reports that night-shift workers can benefit from a realistic but strict sleep schedule. It helps them remain alert during the night shift and allows them to stay awake during the day on days off.

Subjects slept in dark bedrooms at scheduled times: 8:30 a.m. to 3:30 p.m. after the first two night shifts. From 8:30 a.m. to 1:30 p.m. after the third night shift. From 3 a.m. to 12 p.m. on the two weekend days off. And again from 8:30 a.m. to 3:30 p.m. after the final four night shifts.

They also were exposed to five, 15-minute sessions of bright light therapy each night shift. Within two hours after waking up, they went outside for at least 15 minutes of natural light exposure. But they wore dark sunglasses whenever they were outside.

The schedule enabled them to perform well at work and sleep well at home. Contact an AASM-accredited sleep center if you are sleeping on the job or struggling with a shift-work schedule.

Drowsy Plow Driving

The snowstorms hitting the Midwest and Northeast are a nightmare for commuters. Driving would be nearly impossible without the armies of snowplows and salt trucks that come out to rid the streets of snow.

But for the plow drivers who work all night, clearing the streets isn’t their only challenge. The Nashua Telegraph in New Hampshire points out that they also have to fight to stay awake.

Working through the night. Icy streets. Poor visibility. It’s almost a perfect storm for drowsy driving. Especially for those who are clearing long stretches of empty highways.

What’s the extent of the problem? Clearing streets can involve thousands of people in the states and cities with the most snow.

Illinois has more than 3,000 employees working to keep state routes clear. The effort involves more than 482,000 labor hours. The city of Chicago deploys a fleet of 274 trucks to clear city streets.

Chicago gets an average of about 39 inches of snow per year. But that’s nothing compared to the 116 inches of snow that falls on Syracuse annually.

Of course it isn’t just snow plow drivers who are in danger of drowsy driving. Any shift worker is at risk. This includes truck drivers, pilots and police officers.

A shift-work schedule can cause severe sleep problems. The AASM offers these Sleep Tips for Shift Workers as a helpful resource.