ALLERGY, RESPIRATORY
Air Quality Better in Northeast, Midwest
Overweight Moms More Likely to Have Asthmatic Kids
Childhood Food Allergies on the Rise
ALTERNATIVE MEDICINE
Should Your Child Be Seeing a Chiropractor?
Garlic Yields Up Its Health Secret
Grapefruit Compound Inhibits Hepatitis C Virus
ANIMAL CARE
Safe Toys for Dogs
'Comfort Dogs' Come to Emotional Rescue
Beware of Dog Bites
BONES & JOINTS
Genes May Help Drive Rotator Cuff Injury
Human Ancestors Put Best Foot Forward 1.5M Years Ago
Rheumatoid Arthritis a Threat to the Heart
CANCER
Red Meat No No No But Oily Fish Yes Yes Yes
Vitamin D May Improve Melanoma Survival
Physical Activity May Prolong Survival After Colon Cancer
CAREGIVING
TV Watching Doesn't Fast-Track Baby's Skills
Babies Born in High Pollen Months at Wheezing Risk
Recession Scrambling Health Spending in U.S.
CIRCULATORY SYSTEM
Review Confirms Links Between Diet, Heart Health
Laughter Can Boost Heart Health
A Brisk Pace May Keep Stroke at Bay
COSMETIC
Gum Chewing May Cut Craving for Snacks
What to Do If You Have Unsightly Veins
With Psoriasis, the Internet May Offer Hope
DENTAL, ORAL
Gum Disease Might Boost Cancer Risk
Scientists Find Gene for Tooth Enamel
Toothbrushing May Stave Off Heart Woes
DIABETES
Poor Blood Sugar Control After Heart Surgery Impacts Outcomes
Diabetes Linked to Cognitive Problems
Americans Consuming More Sugary Beverages
DIET, NUTRITION
Iced Teas Pose High Risk of Kidney Stones
More Calcium And Dairy Products in Childhood Could Mean Longer Life
Eat Light - Live Longer
DISABILITIES
Could Your Cell Phone Help Shield You From Alzheimer's?
Review Finds Marijuana May Help MS Patients
ENVIRONMENTAL HEALTH
Preparing for a Chlorine Gas Disaster
Global Warming Linked to Heightened Kidney Stone Risk
Global Warming May Bring More Respiratory Woes
EYE CARE, VISION
FDA Goes After Unapproved Eye Washes, Skin Ointments
Sports Eye Injuries Leading Cause of Blindness in Youths
When Corks Fly, Watch the Eyes
FITNESS
Marathoners Go the Distance on Heart Health
When It Comes to Lifting, the Pros Have Your Back
Any Exercise Good After a Heart Attack
GASTROINTESTINAL PROBLEMS
Intestinal Bacteria Trigger Immune Response
HRT Use Raises Risk of Stomach Trouble
Gum Chewing May Speed Colon Surgery Recovery
GENERAL HEALTH
Vinegar Might Help Keep Off Pounds
Keep Fire Safety in Mind as You Celebrate
Internet Program Helps Problem Drinkers
HEAD & NECK
Many Children Will Outgrow Headaches
Zen May Thicken Brain, Thwart Pain
Ski Helmets Encouraged for All
HEALTH & TECHNOLOGY
Using Light Therapy to Silence Harmful Brain Activity
Subway Defibrillators Save Lives
Magnet Therapy May Ease Hard-to-Treat Depression
HEARING
Noise Hurts Men's Hearing More, Study Shows
Summer Sounds Can Lead to Hearing Loss
HEART & CARDIOVASCULAR
Western Diet Linked To Heart Disease, Metabolic Syndrome
Fructose Boosts Blood Pressure, Studies Find
Boosting Vitamin D Can Do a Heart Good
INFECTIOUS DISEASE
Poor Restroom Cleaning Causes Cruise-Ship Sickness
Dry Weather Boosts Odds of Flu Outbreaks
Surgical Masks Could Prevent Flu, Maybe
INFERTILITY
Obesity May Affect Fertility in Young Womene
KID'S HEALTH
School Phys. Ed. Injuries Up 150 Percent
Eating Fish, Breast-Feeding Boost Infant Development
Exercise in Adolescence May Cut Risk of Deadly Brain Tumor
MEN'S HEALTH
Lots of Sex May Prevent Erectile Dysfunction
Exercise May Prevent Prostate Cancer: Study Shows
Physical Activity May Prolong Survival After Colon Cancer
MENTAL HEALTH
Heal Your Life® Tips for Living Well
Cinnamon Breaks Up Brain Plaques, May Hold Key to Fighting Alzheimer’s
Meditation, Yoga Might Switch Off Stress Genes
PAIN
Alleviating Rheumatoid Arthritis
Are We Exercising Pain Away? Not So Much.
Acupuncture, Real or Fake, Eases Back Pain
PHYSICAL THERAPY
PREGNANCY
Woman in America Are Delaying Motherhood, Study Says
Music of Mozart Soothes the Preemie Baby
Sleeping Could Help Women Lose The Baby Fat
SENIORS
Laughter Can Stimulate a Dull Appetite
Money May Matter, Health-Wise, in Old Age
Community Exercise Programs Boost Seniors' Strength
SEXUAL HEALTH
SLEEP DISORDERS
Exercising Throat Muscles May Relieve Sleep Apnea
6 to 8 Hours of Shut-Eye Is Optimal for Health
Sleeping Could Help Women Lose The Baby Fat
WOMEN'S HEALTH
Acupuncture May Help Relieve Polycystic Ovary Syndrome
Exercise During Pregnancy Keeps Newborn Size Normal
How Much Fish to Eat While Pregnant?
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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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