Circadian Rhythms’ Impact on Your Health

Posted by Brigham and Women's Hospital April 26, 2016

The circadian system signals the body to increase production of a certain protein that promotes blood clotting at about the same time as a person normally wakes up.

Circadian rhythms are biological processes that regulate numerous body functions throughout the day and recur according to roughly a 24-hour cycle.

Why do people have an increased risk for heart attacks in the morning? Why is asthma more severe at night? Why are epilepsy symptoms more prevalent at certain times of the day? Research suggests that these and other tendencies are driven by our circadian rhythms (body clock).

Understanding Circadian Rhythms

Circadian rhythms are biological processes that regulate numerous body functions throughout the day and recur according to roughly a 24-hour cycle. The timing of these processes is controlled by the brain’s central clock, the suprachiasmatic nucleus (located in the hypothalamus), as well as peripheral clocks located in virtually all organs and tissues. Although circadian rhythms are inborn, they adjust according to external cues – especially the presence or absence of light.

Studying Their Impact on Health

Researchers at the Brigham and Women’s Hospital Medical Chronobiology Program study how the circadian system impacts our health. They have shown, for example, that the system signals the body to increase production of a certain protein that promotes blood clotting at about the same time as a person normally wakes up. This may partially account for why we observe more heart attacks, stroke, and sudden cardiac death during the early morning hours.

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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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Women’s Sleep Across a Lifetime

Posted by Brigham and Women's Hospital July 25, 2013

There are things that women of all ages can do to get a good night's sleep.

Today’s post is written by Dr. Sandra Horowitz, a neurologist who specializes in sleep disorders at Brigham and Women’s Hospital.

Women lead busy lives: we work, have babies, raise families, and take care of our sick and elderly family members. Juggling these numerous roles, combined with hormonal changes due to menarche, menopause, and pregnancy, as well as other health conditions, can affect a woman’s ability to fall asleep and stay asleep.  Despite these challenges, there are things women of all ages can do to get a good night’s sleep.

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A Link between Melatonin Levels and Diabetes?

Posted by Brigham and Women's Hospital April 18, 2013

The amount of melatonin a person secretes during sleep may predict their likelihood of developing type 2 diabetes.

Many of us take melatonin to get a good night’s sleep. Now, new research from Brigham and Women’s Hospital (BWH) suggests that melatonin may play another important role in our health. Led by Dr. Ciaran McMullan, a researcher in the Renal (Kidney) Medicine Division in the Department of Medicine at BWH, the study finds that the amount of melatonin a person secretes during sleep may predict their risk of developing type 2 diabetes.

Melatonin is a hormone that is produced by the brain and secreted into your bloodstream. Melatonin, mainly produced at night, helps regulate your body’s sleep cycles.

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Your Health: Ten Things That Really Matter, Tip #10

Posted by Brigham and Women's Hospital February 28, 2013

It's important to know your wellness numbers and which ones are most important to you.

To conclude American Heart Month, we’ve been featuring health tips that were presented by Brigham and Women’s Hospital women’s health experts, Dr. JoAnne Foody and Dr. Paula Johnson, at the Boston Go Red for Women Educational Forum. (Go Red for Women, sponsored by the American Heart Association, occurs each February to educate all women about the need to take care of their hearts.)

Men take note, these tips can benefit you, too – heart disease is the leading cause of death for both men and women. Today, we present the final tip.

10. KNOWING YOUR NUMBERS IS NOT ENOUGH: KNOW WHICH NUMBERS ARE MEANINGFUL TO YOU.

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Making Headway on Beta-Blockers and Sleep

Posted by Brigham and Women's Hospital November 14, 2012

Patients who take high blood pressure medication often have trouble sleeping.

It’s three in the morning and you’re wide awake.  If you’re taking a medication known as a beta-blocker, you may find this happens more often than you’d like.

Over 20 million people in the United States take beta-blockers, a medication commonly prescribed for cardiovascular issues, anxiety, hypertension (high blood pressure), and more. Many of these same people also have trouble sleeping.  Beta-blockers are known to block the body’s production of melatonin, a hormone that helps regulate the body’s sleep cycles.  Researchers at Brigham and Women’s Hospital (BWH) have found that giving patients melatonin supplements at night improved sleep in patients taking beta-blockers.

“Beta-blockers have long been associated with sleep disturbances, yet until now, there have been no clinical studies that tested whether melatonin supplementation can improve sleep in these patients,” explained Frank Scheer, PhD, MSc, an associate neuroscientist at BWH, and principal investigator on this study. “We found that melatonin supplements significantly improved sleep.”

The research team analyzed 16 patients who regularly took beta-blockers as treatment for high blood pressure. The study subjects were given either a melatonin supplement or placebo before bed each night; neither the subjects nor the researchers knew which pill the patients were taking.

Analyzing the subjects’ sleep patterns, researchers found, on average, that subjects who received the melatonin supplement slept 37 minutes longer compared to those who received a placebo.  Patients taking melatonin also spent more time in Stage 2 sleep, the most prevalent stage.  There was no significant difference in the amount of time spent in the other stages of sleep between patients on a placebo and those taking melatonin.

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Start Your Back-to-School Sleep Schedule Today!

Posted by Brigham and Women's Hospital September 4, 2012

A good night's rest is essential for the physical and mental health of everyone in your family.

The beginning of another school year has started, prompting families to prepare for back-to-school routines, including adjustments to the family’s sleep schedule. A good night’s rest is essential for the physical and mental health of everyone in the family, but getting the appropriate quality and amount of rest is not always an easy task.

Keep in mind that adults require about eight hours of sleep per night, while children require between nine and 12 hours. “Commit to getting the right amount of sleep, as a family,” said Dr. Atul Malhotra, associate professor of medicine at Brigham and Women’s Hospital. “Sleep deprivation can have detrimental effects on school and work performance, safety while driving and working, the immune system, cognitive processes, and mood.”

To help the family get back to a healthy sleep schedule, Dr. Malhotra, suggests:

  • Begin the transition from summer sleep schedule to back-to-school sleep schedule before school begins. This change takes some time for adjustment.
  • Maintain a consistent sleep schedule to regulate the body’s sleep cycle. Define bed times and stick to them consistently, and avoid sleeping late on weekends.
  • Dim the lights in the evening as bedtime approaches and avoid night-lights. Light exposure at night can interfere with the body’s natural circadian clock and the biological signal that it is time to sleep. On the other hand, exposure to light during the day helps signal the brain into the right sleep-wake cycle.

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Sleep and Aging: Why Can’t We Stay Asleep as We Get Older?

Posted by Brigham and Women's Hospital August 24, 2012

The problem for older adults isn’t falling asleep, it’s staying asleep.

Contributor: Elizabeth Klerman, MD, PhD, is the Director of the Analytic Modeling Unit within the Division of Sleep and Circadian Disorders at Brigham and Women’s Hospital and Associate Professor of Medicine at Harvard Medical School.  Her research interests include the impact of circadian rhythms on sleep.

Google the terms “sleep and aging” and you’ll receive millions of search results, a good indication of how common insomnia, or the inability to sleep through the night, is among older adults. In a National Sleep Foundation survey of adults aged 55 and older, one-third of people aged 55-64 and one quarter of people aged 65-84 reported that their sleep quality had worsened over time.

There are many reasons why older adults have more trouble sleeping. Health conditions such as restless leg syndrome, chronic pain, or sleep apnea may be causes. However, even healthy people may experience sleep problems as they get older.

How Sleep Changes as We Age

To understand why healthy, older adults have trouble sleeping through the night, researchers at Brigham and Women’s Hospital compared data on sleep patterns in younger (21-30 years) and older adults (aged 60-74 years) from several different studies.

“Our study found that both young and old people had no trouble falling asleep, but the older population was four times more likely to wake up throughout the night when compared to younger people,” explained Dr. Klerman, the lead researcher on this study.

During a typical night’s sleep, your body actually goes through several different cycles of alertness. These include wakefulness; rapid eye movement (REM) sleep, associated with dreaming; and non rapid eye movement (NREM) sleep, which accounts for about 75 percent of an adult’s sleep. The BWH researchers confirmed that a primary cause of sleep problems in healthy, older adults is difficulty in remaining in the NREM sleep state.

Surprising Results about Sleep in Older Adults

The researchers also found, contrary to expectations, that once an individual had awakened, the ability to fall back asleep was not significantly different between younger and older adults. These results suggest that the problem in healthy, older adults is remaining asleep, not falling back asleep once they’ve awakened during the night. This finding will impact how future sleep treatments are developed for this population.

Have you noticed changes in your sleep patterns as you’ve gotten older? How are these changes affecting your life?

To learn more about sleep disorders and our research on sleep visit the BWH Division of Sleep and Circadian Rhythm Disorders.

 

– Jamie R

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Sleep and Productivity: A Delicate Balance

Posted by Brigham and Women's Hospital August 9, 2012

Insufficient sleep, even if you don't feel tired, can impact your productivity.

Think that you can get more work done by skimping on shut eye? Not necessarily.

Brigham and Women’s Hospital (BWH) researchers collected and analyzed data on visual search tasks from 12 participants over a one-month study that took place in the BWH Center for Clinical Investigation.  In the first week, all participants were scheduled to sleep 10-12 hours per night. For the following three weeks, the participants were scheduled to sleep the equivalent of 5.6 hours per night. They also had their sleep times scheduled on a 28-hour cycle, mirroring chronic jet lag.

Throughout the study, the participants took performance tests several times each day to test how quickly and accurately they could compare two pictures on a computer screen and detect a difference between them.  While the accuracy of the participants stayed fairly constant, they were slower to identify the relevant information as the weeks went on.

“We found that the longer the participants were awake, the more slowly they identified the difference between the two pictures in the test,” says Dr. Jeanne Duffy, a researcher in the BWH Division of Sleep Medicine and senior author of this study. “Additionally, during the biological night time (from about 12 a.m. to 6 a.m.), participants, who were unaware of the time throughout the study, performed tasks more slowly than they did during the daytime.”

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