ALLERGY, RESPIRATORY
Obesity May Raise Kids' Allergy Risk
Know Your Asthma Triggers
Keep Asthma, Allergies at Bay for the Holidays
ALTERNATIVE MEDICINE
Alternative Treatments May Boost IVF Success
Pain-Relieving Powers of Acupuncture Unclear
Relaxation Tapes or Mozart Lower Blood Pressure
ANIMAL CARE
Safe Toys for Dogs
Beware of Dog Bites
'Comfort Dogs' Come to Emotional Rescue
BONES & JOINTS
Gene Therapy May Ease Rheumatoid Arthritis
Genes May Help Drive Rotator Cuff Injury
B Cells Can Act Alone in Autoimmune Diseases
CANCER
Vitamin E, Selenium and Soy Won't Prevent Prostate Cancer
Gene Studies Reveal Cancer's Secrets
Hypnosis Cuts Hot Flashes for Breast Cancer Survivors
CAREGIVING
Depression, PTSD Common Among Lung Transplant Patient Caregivers
Moms Who Breast-Feed Less Likely to Neglect Child
Older Caregivers Prone to Worse Sleep Patterns
CIRCULATORY SYSTEM
Night Shift Work Hard on the Heart
Salt Boosts Blood Pressure in High-Risk Patients
Potassium-Rich Foods May Cut Stroke, Heart Disease Risk
COSMETIC
What to Do If You Have Unsightly Veins
Study Evaluates Laser Therapies for Hair Removal
Get Sugared!.... Its a sweet choice for hair removal
DENTAL, ORAL
Periodontal Disease Impacts Whole Health
Good Oral Hygiene May Protect Against Heart Infections
Sports Drinks May Be Tough on Teeth
DIABETES
Treatment for Type 2 Diabetes Updated
Arthritis Hits More Than Half of Diabetics
Findings Challenge Tight Glucose Control for Critically Ill Patients
DIET, NUTRITION
Whole Grains, Bran May Fight Hypertension in Men
Want to Stop Cancer? You Can, Experts Say
Leafy Greens Top Risky Food List
DISABILITIES
Could Your Cell Phone Help Shield You From Alzheimer's?
Review Finds Marijuana May Help MS Patients
ENVIRONMENTAL HEALTH
Main Ingredients in Household Dust Come From Outdoors
Vest Monitors 'Individual' Air Pollution
Controversial Chemical Lingers Longer in the Body
EYE CARE, VISION
Unconscious Learning: In the Eye of the Beholder?
When Corks Fly, Watch the Eyes
Decorative Halloween Eye Lenses May Pose Serious Risks
FITNESS
Early Exercise Boosts Outcomes for ICU Patients
Tai Chi: An Ideal Exercise for Many People with Diabetes
Exercise Keeps the Brain Young
GASTROINTESTINAL PROBLEMS
Gum Chewing May Speed Colon Surgery Recovery
Olive Oil May Protect Against Bowel Disease
HRT Use Raises Risk of Stomach Trouble
GENERAL HEALTH
Kids With Vitamin D Deficiency Linked to Heart Trouble
Heart Disease May Be Prevented By Taking Fish Oils, Study Shows
Winter's Bitter Cold Poses Health Dangers
HEAD & NECK
Ski Helmets Encouraged for All
Many Children Will Outgrow Headaches
Zen May Thicken Brain, Thwart Pain
HEALTH & TECHNOLOGY
Imaging Sheds Light on How Acupuncture Works
Airport Full Body Scanners Pose No Health Threat: Experts
Magnet Therapy May Ease Hard-to-Treat Depression
HEARING
Summer Sounds Can Lead to Hearing Loss
Noise Hurts Men's Hearing More, Study Shows
HEART & CARDIOVASCULAR
Coffee Is Generally Heart-Friendly
Implanted Defibrillators Boost Long-Term Survival
Laughter Can Boost Heart Health
INFECTIOUS DISEASE
Swine Flu Closes Three Schools in NYC
Swine Flu Now Reported in All 50 States
Dry Weather Boosts Odds of Flu Outbreaks
INFERTILITY
Obesity May Affect Fertility in Young Womene
KID'S HEALTH
Backpack Safety Should Be on Back-to-School Lists
Help Your Kids Stay Active
Quick Orthopedic Repair Can Save Young Shoulders
MEN'S HEALTH
Low Vitamin D Levels May Boost Men's Heart Attack Risk
Exercise May Prevent Prostate Cancer: Study Shows
Whole Grains, Bran May Fight Hypertension in Men
MENTAL HEALTH
Daily dose of beet juice promotes brain health in older adults
Massage Fosters Healing in Bereaved Relatives
Teen Internet Addicts More Likely to Self-Harm: Study
PAIN
Tai Chi May Help Ease Fibromyalgia
'Cell Phone Elbow' -- A New Ill for the Wired Age
Alleviating Rheumatoid Arthritis
PHYSICAL THERAPY
PREGNANCY
Before Conceiving, Take Folic Acid for One Full Year
Expectant Mom's Exercise Keeps Newborn's Birth Weight Down
Woman in America Are Delaying Motherhood, Study Says
SENIORS
Boost In Elderly Population Will Be Felt Worldwide
The Juice From Beetroots May Boost Stamina
Nighttime Urination Linked to Higher Death Rate Among Elderly
SEXUAL HEALTH
SLEEP DISORDERS
Exercising Throat Muscles May Relieve Sleep Apnea
6 to 8 Hours of Shut-Eye Is Optimal for Health
Better Sleep, Grades Seem to Go Up
WOMEN'S HEALTH
A Brisk Pace May Keep Stroke at Bay
Heal Your Life® Tips for Living Well
Mom and Baby Alike May Benefit From Exercise
Add your Article

Night Shift Work Hard on the Heart

MONDAY, March 2 -- Working the night shift might lead to hormonal and metabolic changes that raise risks for obesity, diabetes and heart disease, researchers say.

"In the long run, the physiological impact of shift work on several markers involved in the regulation of body weight -- leptin, insulin, cortisol -- seems to contribute to the increased risk for the development of diabetes, cardiovascular disease and obesity," said study author Frank Scheer, an instructor of medicine in the division of sleep medicine at Brigham and Women's Hospital and Harvard Medical School, in Boston.

Scheer and his team report the findings in the March 2 online issue of the Proceedings of the National Academy of Sciences.

The authors point out that about 8.6 million Americans perform shift work, which the National Sleep Foundation defines as any type of schedule that falls outside the standard nine-to-five norm for business hours. In the United States, factory workers, hospital staff, policemen, firefighters, pilots, road crews and truck drivers are some of the positions that commonly entail some degree of shift work.

This type of work has been previously associated with gastrointestinal problems, fatigue and poor sleep, the researchers noted. Such complications are thought to arise from a chronic disconnect between the waking and eating habits the work demands and the body's innate 24-hour sleep/wake clock, commonly known as the circadian rhythm.

To explore how such a misalignment might raise the risk for developing serious health issues, Scheer and his colleagues conducted a laboratory test designed to mimic the acute effects of jet lag and/or the chronic impact of regular shift work.

In the experiment, the bodily responses of five men and five women were tracked as they stuck to an ever-changing sleep/eat schedule for 10 days.

By the study's conclusion, all the volunteers had eaten and slept across all phases of the circadian cycle, as they followed a daily schedule artificially fashioned along 28-hour blocks.

The results: circadian misalignment provoked a drop in levels of the weight-regulating hormone leptin. Plummeting leptin levels could hasten the onset of obesity and heart disease by prompting increases in appetite and decreases in activity, the researchers said.

Furthermore, changes in blood sugar levels and insulin levels also occurred, resulting in impaired glucose tolerance and decreased insulin sensitivity.

In particular, three participants with no prior history of diabetes developed glucose levels that resembled those of pre-diabetic people after eating on the misaligned schedule. Daytime blood pressure levels were also found to be elevated among these volunteers.

The degree of hormonal change was highest when participant schedules were set 12 hours off the normal sleep/wake cycle -- that is, when participants were asked to sleep throughout the day and stay awake through the night.

Yet despite the strength of the findings, Scheer cautioned that more research is needed before drawing too many conclusions.

"First of all, this is an in-laboratory study of short duration," he observed. "So we don't yet know if circadian misalignment has a similar impact in the long run in a real-life setting where people are performing night shift work."

"We also need to look at how different people might respond differently," Scheer noted. "Because shift work typically affects people's alertness levels, and GI functioning, and those who don't cope well with this are likely to drop out. Which means that those who continue with this kind of work might not be so susceptible to such problems, and may be less sensitive to this kind of misalignment. These are all questions for the future."

For the time being, Dr Joseph Bass, an assistant professor of medicine at Northwestern University's Feinberg School of Medicine in Chicago, agreed it is too soon to draw direct connections between shift work and specific health risks.

"However, having said that, this isn't smoke and mirrors," he said. "Our internal biological clocks represent a whole area of biology that is as critical as blood pressure or breathing. And this work does provide us with a plausible biological mechanism that may underlie and cumulatively contribute to the occurrence of metabolic disorders in certain individuals, because of their work patterns, or because of traveling, or simply because they ignore the normal light cycle."

Alan Mozes

More information

For more on night shift work and sleep, visit the National Sleep Foundation.



SOURCE: Frank Scheer, Ph.D, instructor, medicine, division of sleep medicine, department of medicine, Brigham and Women's Hospital, and Harvard Medical School, Boston; Joseph Bass, M.D., Ph.D., assistant professor, medicine, Northwestern University Feinberg School of Medicine, Chicago; March 2, 2009, Proceedings of the National Academy of Sciences, online

Last Updated: March 03, 2009

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