Night Shift Workers – Beware of Driving Crash Risk

Posted by Brigham and Women's Hospital February 11, 2016

 Night shift workers have many more motor vehicle crashes than day workers, particularly during the commute home.

Night shift workers have many more motor vehicle crashes than day workers, particularly during the commute home.

Researchers at Brigham and Women’s Hospital (BWH) and the Liberty Mutual Research Institute for Safety recently found that 37.5 percent of drivers participating in a test drive after working the night shift were involved in a near-crash event. The same drivers, with normal sleep the night before the test, had zero near-crashes.

“Drowsy driving is a major, and preventable, public health hazard,” says Charles A. Czeisler, PhD, MD, FRCP, Chief of the Division of Sleep and Circadian Disorders at BWH, and corresponding author of the study. “These findings help to explain why night shift workers have so many more motor vehicle crashes than day workers, particularly during the commute home. Night shift workers should be advised of the hazards of drowsy driving and seek alternate forms of transportation after night shift work.”

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Improve Glucose Tolerance by Eating and Working Earlier in the Day

Posted by Brigham and Women's Hospital September 24, 2015

Eating late at night and working overnight both increase the risk of developing type 2 diabetes.

Contributor: Frank A. J. L. Scheer, PhD, is a neuroscientist and Director of the Medical Chronobiology Program at Brigham and Women’s Hospital (BWH).

Research shows that eating later in the day lowers the body’s ability to regulate blood sugar levels, also known as low glucose tolerance. The study, published in Proceedings of the National Academy of Sciences in March 2015, also found that night shift workers who sleep during the day and work overnight had lower glucose tolerance than those who are awake during the day and sleep at night. This, in turn, can impact health issues such as weight gain, insulin resistance, and the risk for developing Type 2 diabetes.

The study compared circadian rhythms, sleep/wake cycles, and mealtimes to blood glucose levels in 14 healthy participants. All subjects participated in two protocols. In one protocol, the individuals were awake during the day, had their first meal at 8 a.m., their last meal at 8 p.m., and slept at night. In the second, they slept during the day, had their first meal at 8 p.m., stayed up all night, and had their last meal at 8 a.m.

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Rotating Shift Work May Increase Health Risks in Women

Posted by Brigham and Women's Hospital March 10, 2015

Rotating shift work may increase a woman’s risk of dying from heart disease or lung cancer.

New Brigham and Women’s Hospital (BWH) research has found that long-term rotating shift work may increase a woman’s risk of dying from heart disease or lung cancer.

To examine the impact of rotating night shift work on mortality, BWH epidemiologist Dr. Eva Schernhammer and her research team analyzed 22-year medical histories of nearly 75,000 female nurses from the Nurses’ Health Study. The composition of the Nurses’ Health Study – exclusively female nurses – was particularly advantageous for Dr. Schernhammer’s purposes, as many nurses have rotating-shift schedules.

Compared to nurses who never worked night shifts, the researchers found that nurses who regularly worked rotating shifts for 6 to 14 years were 19 percent more likely to die from heart disease. (For this study, a rotating-shift worker was defined as someone who worked at least three nights per month, in addition to shifts at other times of the day.) Women who worked rotating shifts for 15 years or more were 23 percent more likely to die from heart disease and 25 percent more likely to die from lung cancer. The study also found that rotating shift workers were slightly more likely to die sooner, regardless of the cause.

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Beware of Blue-Light Before Sleep

Posted by Brigham and Women's Hospital January 22, 2015

Using certain light-emitting electronic devices in the hours before bedtime may negatively impact overall health.

Contributors: Anne-Marie Chang, PhD, is an associate neuroscientist within Brigham and Women’s Hospital (BWH) Division of Sleep and Circadian Disorders. Charles Czeisler, MD, PHD, is Chief of BWH’s Division of Sleep and Circadian Disorders.

Can the way you read before bedtime affect the quality of your sleep?

Recent research from Brigham and Women’s Hospital (BWH) suggests that the use of light-emitting electronic devices – tablets, some e-readers, smart phones, and laptops – in the hours before bedtime can negatively impact overall health, alertness, and the circadian clock, which synchronizes the daily rhythm of sleep to external environmental cues.

“We found the body’s natural circadian rhythms were interrupted by the short-wavelength enriched light, otherwise known as blue light, from these electronic devices,” said Anne-Marie Chang, PhD, corresponding author and associate neuroscientist in BWH’s Division of Sleep and Circadian Disorders. “Participants reading a light-emitting e-book took longer to fall asleep and had reduced evening sleepiness, reduced melatonin secretion, later timing of their circadian clock, and reduced next-morning alertness.”

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Sleep – The Third Pillar of Good Health

Posted by Brigham and Women's Hospital July 29, 2014

Charles Czeisler, PhD, MD, Professor of Sleep Medicine

Most of us understand that good nutrition and exercise are essential to good health; however, many of us overlook the importance of sleep. Dr. Charles Czeisler, Chief, Division of Sleep and Circadian Disorders at Brigham and Women’s Hospital, explains that sleep is essential to both our brains and our bodies.

During sleep, the brain is flushed of toxins and new learning experiences are integrated, says Dr. Czeisler. Inadequate sleep, he continues, can have wide-ranging effects on our physical health, including a dampening of the immune response, disruption of hormones that regulate weight, reduction in the effectiveness of insulin metabolism, and increased risk for calcification of the arteries. Dr. Czeisler also describes how artificial light exposure can lead to shortened sleep cycles or insomnia by disrupting our circadian rhythms.

Watch a video of Dr. Czeisler discussing the impact of sleep on health and innovative sleep research being conducted at Brigham and Women’s Hospital.

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Blue Light Boosts Alertness, Study Shows

Posted by Brigham and Women's Hospital March 27, 2014

Blue light

Blue light exposure during the day immediately improves alertness and performance.

Sometimes we feel a little sluggish, when it’s hard to get motivated or get ahead of the day’s tasks. What if there was a simple way to perk up without caffeine, sugar, or breaking a sweat?

Science tells us there is.

What is blue light and what does it do?

Brigham and Women’s Hospital (BWH) researchers have found that exposure to short-wavelength (blue) light, which is abundant in daylight, during the biological day directly and immediately improves alertness and performance.

“Our previous research has shown that blue light is able to improve alertness during the night, but our new data demonstrates that these effects also extend to daytime light exposure,” says Shadab Rahman, PhD, a researcher in BWH’s Division of Sleep and Circadian Disorders and the study’s lead author. “These findings demonstrate that prolonged blue light exposure during the day has an alerting effect.”

Blue light stimulates the brain more than other light.

To determine which wavelengths of light were most effective in warding off fatigue, the BWH researchers teamed with George Brainard, PhD, a professor of neurology at Thomas Jefferson University, who developed the specialized light equipment used in the study. During a 6.5 hour period, one group of study participants was continuously exposed to blue light while a comparison group was exposed to an equal amount of medium-wavelength (green) light. Throughout the exposure period, brain electrical activity was monitored, reaction times were measured, and participants were asked to rate how sleepy they felt.

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Morning Heart Attacks: Blame It on Your Body Clock

Posted by Brigham and Women's Hospital December 4, 2013

Have you ever wondered why most heart attacks occur in the morning?

Have you ever wondered why most heart attacks occur in the morning? According to recent research from Brigham and Women’s Hospital (BWH) and Oregon Health & Science University, it turns out that your body clock may play a contributing role.

“Our findings suggest that the circadian system, the internal body clock, may contribute to the increased risk for cardiovascular events in the morning,” says study author Frank A.J.L. Scheer, PhD, MSc, Director of the Medical Chronobiology Program at BWH.

Your circadian system regulates and coordinates many of your body’s functions, including metabolism. It tells your body when you should sleep and when you should eat. In this particular study, the researchers found that the body clock drives day/night variations in the quantity of a protein known to be a risk factor for heart attacks and ischemic strokes. The protein is called plasminogen activator inhibitor-1 (PAI-1). It inhibits the breakdown of blood clots and, thus, is a major risk factor for blood clotting.

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Is the Night Shift Bad for Your Health?

Posted by Blog Administrator April 23, 2012

Rotating shift workers may be at greater risk for obesity and diabetes.

Contributor: Dr. Orfeu M. Buxton is an associate neuroscientist at Brigham and Women’s Hospital (BWH). He studies the health consequences of chronic sleep deficiency, especially cardiometabolic outcomes.

You’ve often been told about the importance of getting enough sleep. But how often have you been told about the importance of when to sleep?

Brigham and Women’s Hospital (BWH) Division of Sleep Medicine study showed that a combination of insufficient sleep and sleep patterns that disagree with our body’s biological clock (circadian rhythm) may lead to an increased risk of Type 2 diabetes and obesity. This is unwelcome news for rotating shift workers, a group particularly prone to not getting enough sleep, and, out of necessity, to sleeping at abnormal times.

A circadian rhythm is a biological process that regulates and coordinates many of your body’s functions, including metabolism. It tells your body when you should sleep and when you should eat. So, what would happen if you defied your body’s instinctive cues?

To address this question, researchers studied the impact of a rotating shift worker’s sleep schedule in a tightly controlled lab environment. At first, participants were getting an optimal amount of sleep at the optimal time – about 10 continuous hours each day, with each session starting after sunset. Next, participants were only allowed to sleep 5.6 hours each day, with the sleep occurring at varying times of day and night – to mimic the circadian disruptions that are experienced by a rotating shift worker (or someone with recurrent jet lag).

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