воскресенье, 28 ноября 2010 г.

Higher BMI Linked to Less Sleep

A study from Walter Reed Medical Center shows that higher BMI is linked to getting less sleep. Not only is sleep quality important to maintain a healthy weight, but sleep duration is also important to keep weight stable. Results of a newer study show that people who sleep less have a higher body mass index (BMI).
Findings presented Sunday, May 17, 2009 at the American Thoracic Society's 105th International Conference in San Diego, show that fourteen nurse volunteers enrolled in the Integrative Cardiac Health Project at the Walter Reed Medical Center had higher BMI’s as the result of less sleep, compared to nurses who slept longer.
The researchers engaged the nurses in nutritional counseling sleep and stress management, and exercise training, analyzing total activity, body temperature, and body position; facilitated by use of an actigraphy armband. The study revealed that even increased activity did not equate to lower BMI for the nurses who slept less.
Lead investigator Arn Eliasson, M.D. says, "When we analyzed our data by splitting our subjects into 'short sleepers' and 'long sleepers,' we found that short sleepers tended to have a higher BMI, 28.3 kg/m2, compared to long sleepers, who had an average BMI of 24.5. Short sleepers also had lower sleep efficiency, experienced as greater difficulty getting to sleep and staying asleep."
Additionally, people who sleep less may be more stressed, leading them to eat more, thus accounting for the increased BMI associated with less sleep. "Higher perceived stress may erode sleep. Stress and being less rested may cause these individuals to be less organized than normal weight individuals, meaning they would have to make more trips and take more steps to accomplish the same tasks. This might add to their stress and encourage other unhealthy behaviors like stress eating," says Dr. Eliasson.
Other unhealthy behaviors might explain the exact link between higher BMI and increased weight in people who sleep less. The researchers are also planning studies to measure hormone levels. The authors speculate that less sleep may disrupt the balance of the hormone leptin that tells us when we have had enough to eat, leading to increased food consumption and higher BMI.

среда, 24 ноября 2010 г.

Insomnia in women with breast cancer linked to heart rate

This study is the first to analyze both hormonal and autonomic responses in metastatic breast cancer patients suffering from insomnia.
Westchester, Ill. –A study in the October 15 issue of the Journal of Clinical Sleep Medicine shows that respiratory sinus arrhythmia (RSA) is a significant predictor of insomnia in women with breast cancer and confirmed that longer nocturnal wake episodes were associated with a flatter diurnal cortisol slope.
Results of this study confirmed a relationship between frequent awakenings and abnormal cortisol (a steroid hormone that regulates blood pressure), rhythms in metastatic breast cancer, thus concluding that a disrupted cortisol rhythm may have serious medical implications in women with breast cancer.
With the addition of demographics, disease severity and psychological variables, findings suggest that Vagal regulation, assessed via RSA, an important marker of parasympathetic tone, is the most consistent and significant predictor of sleep continuity disturbance. Diminished RSA has been associated with both worse medical and psychiatric health. Previous studies suggest that RSA is associated and may even be predictive for insomnia in healthy subjects.
“It was surprising to see that the strongest association was between a parasympathetic nervous system dysregulation and sleep problems even after we considered patients’ age, their disease severity, type of treatment and psychological variables such as pain and stress,” said the study’s lead author, Oxana Palesh, PhD, Research Assistant Professor at the University of Rochester Cancer Center.
Insomnia symptoms were associated with a lower baseline of RSA. Lower RSA is associated with decreased parasympathetic functioning in insomniacs, and weakened parasympathetic functioning is associated with increased stress and decreased emotional regulation.
The study included 99 women who had metastatic breast cancer or recurrent breast cancer and who were over the age of 45. Thirty-nine patients took antidepressant medications in this study, and 19 took medications specifically prescribed for treating disrupted sleep during study baseline. Participants collected saliva for cortisol measurement for two days, completed questionnaires, wore actigraphs to monitor their sleep-wake cycles for three days, and participated in the Trier Social Stress Task (TSST) approximately one-to-two weeks after the cortisol baseline collections. The TSST is a standardized social and cognitive stress test. Demographic and cancer diagnosis history was collected from the women through self-report.
Heart rate dysregulation (diminished or low respiratory sinus arryhthmia) during a stress task was associated with four objective measures of sleep disruption: sleep efficiency, wake after sleep onset, average number of awakenings and average length of waking episode.
Estimates from two nights of actigraphy indicate that participants spent about eight hours in bed and had wakefulness after sleep onset (WASO) of more than 71 minutes. They also had an average of 15 wake episodes each night with an average duration of 4.81 minutes.
While demographics explained some portion of the development of sleep disruption, four of the six sleep parameters examined (Sleep efficiency, wakefulness after sleep onset, mean number of waking episodes and average length of waking episodes) were best explained by low RSA.
In healthy people, cortisol levels peak early in the morning and level-out by the end of the day. However, in one-third to two-thirds of women with metastatic breast cancer, circadian rhythms are disrupted and diurnal cortisol slopes are either flattened, have multiple peaks, or are elevated at the end of the day. In the non-cancer population, evidence shows that people with insomnia have an elevated response to stress in general. Psychiatric disorders, including major depression, are linked with hypothalamic-pituitary-adrenal axis (HPA) dysregulation. Past research has linked insomnia to activation of the stress-response system, which results in an increased level of cortisol.
Sleep disruption is two to three times more common in cancer patients than in the general population; these disturbances may exacerbate concurrent cancer and/or treatment related symptoms such as fatigue, mood disturbance, and gastrointestinal distress, psychiatric illness and may lead to reduce quality of life and overall health.
According to Palesh, one of the best interventions for regulation of autonomic functioning is diaphragmatic breathing. Any number of stress management techniques would be effective, including biofeedback treatment, hypnosis, visualization exercises, meditation, progressive muscle relaxation and yoga.

пятница, 19 ноября 2010 г.

Poor Night's Sleep Increases Odds of Stroke, Heart Attack

Failure to get a good night's sleep can boost the odds of having a stroke or heart attack. Researchers say poor quality sleep increases inflammatory hormones that lead to poor blood vessel health. Past studies have looked at acute sleep deprivation that occurs for more than 24 hours. The new study shows an increased risk of heart attack and stroke that can happen from six or less hours of good sleep.

Less than Six Hours of Sleep Boosts Inflammatory Markers

For the study, researchers measured inflammatory markers in the bloodstream, matching their findings with the Pittsburgh Sleep Quality Index survey and hours of sleep.
Fibrinogen, IL-6 and C-reactive protein, inflammatory markers that can mean poor blood vessel health were found to be higher in people who reported less than six hours of sleep, compared to those getting six to nine hours. C-reactive protein levels that are widely used to gauge a person’s risk for heart attack and stroke were about 25 percent higher in people sleeping less.
Alanna Morris, MD, a cardiology fellow at Emory University School of Medicine says, "Most of the studies looking at the body's response to lack of sleep have looked at subjects who have been acutely sleep deprived for more than 24 hours in experimental sleep laboratories. Nothing of this sort has been investigated in epidemiologic studies.”
Dr. Morris says, "For people who got little sleep, the C-reactive protein levels were increased, but still in the range of what health authorities would consider low to intermediate risk. However, our study population represents a community-based population [as opposed to patients in the hospital or with known cardiovascular disease], so they have overall lower risk and lower C-reactive protein levels than many of the high risk populations in other studies."
Previous research finds sleeping seven or more hours a night leads to a longer life. The new study lends insight into why sleeping less is tightly linked to high blood pressure, obesity, diabetes and psychological stress, but "It remains uncertain whether short sleep duration contributes directly to cardiovascular mortality, or whether it is a mediating or moderating factor," explains Morris.
Even after correcting for other risk factors like stroke, obesity and diabetes, poor quality sleep was still found to raise inflammation associated with poor blood vessel health. The findings that poor sleep could increase the chances of stroke and heart attack come from a survey of 525 middle-aged people participating in the Morehouse-Emory Partnership to Eliminate Cardiovascular Health Disparities (META-Health). The findings are presented by Dr. Morris today at the American Heart Association Scientific Sessions in Chicago.