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Recent research: lifestyle - five papers on sleep, exercise & stress management

Here are five papers on lifestyle and the benefits of making healthy choices.  The first by Cohen et al on sleep habits and susceptibility to the common cold, showed increased risk of developing a cold after infection for those with shorter sleep duration.  Interestingly the increased risk was even greater for those with poor sleep efficiency.  Sleep efficiency is calculated by dividing the time spent asleep by the time spent in bed trying to sleep.  The Good Knowledge section of this website contains useful information on assessing and treating sleep difficulties.

There are then three papers on exercise.  The first by Suia et al is unusual - it's a longditudinal rather than a cross-sectional study on significantly reduced risk of developing depressive symptoms at subsequent long term follow-up in those who were initially physically fitter (independently of other clinical predictors).  The next paper by Iliffe et al comments "The health benefits of exercise are so great that it is probably the most important self help treatment available. Regular exercise reduces the risk of cardiovascular and respiratory disease, type 2 diabetes, some cancers, and death from all causes. Regular physical activity and structured exercise can also reduce falls and injuries, and it is a key factor in the prevention and management of osteopenia and osteoporosis. It also promotes mental wellbeing and helps people to manage their weight."  The authors then go on to discuss a linked paper on a helpful exercise-on-prescription programme in primary care.  Finally in this sequence of papers on exercise, Brooks and Erith look at the value of warm-up regimes in reducing exercise injuries.  The paper they refer to is interesting in showing benefits from a warm-up programme (something research on this subject has often failed to do).  The 20 minute duration of the warm-up is possibly a little daunting for a typical leisure time exerciser.

The fifth of these papers on "lifestyle" is by Orth-Gomer and colleagues and is another startling vindication of running broad-based stress management programmes to save lives.  Women hospitalized for coronary heart disease were randomized to treatment as usual or to treatment plus a 20 session stress management group.  At seven year follow-up, death rates in the women given the stress management training were only about a third of the death rates in women simply given treatment as usual.  This is a huge difference and parallels the more than halving of mortality reported recently through using a similar style intervention for women with breast cancer.  Health care providers and health care users please note.  

Cohen, S., W. J. Doyle, et al. (2009). "Sleep Habits and Susceptibility to the Common Cold." Arch Intern Med 169(1): 62-67.  [Abstract/Full Text
Background Sleep quality is thought to be an important predictor of immunity and, in turn, susceptibility to the common cold. This article examines whether sleep duration and efficiency in the weeks preceding viral exposure are associated with cold susceptibility. Methods A total of 153 healthy men and women (age range, 21-55 years) volunteered to participate in the study. For 14 consecutive days, they reported their sleep duration and sleep efficiency (percentage of time in bed actually asleep) for the previous night and whether they felt rested. Average scores for each sleep variable were calculated over the 14-day baseline. Subsequently, participants were quarantined, administered nasal drops containing a rhinovirus, and monitored for the development of a clinical cold (infection in the presence of objective signs of illness) on the day before and for 5 days after exposure. Results There was a graded association with average sleep duration: participants with less than 7 hours of sleep were 2.94 times (95% confidence interval [CI], 1.18-7.30) more likely to develop a cold than those with 8 hours or more of sleep. The association with sleep efficiency was also graded: participants with less than 92% efficiency were 5.50 times (95% CI, 2.08-14.48) more likely to develop a cold than those with 98% or more efficiency. These relationships could not be explained by differences in prechallenge virus-specific antibody titers, demographics, season of the year, body mass, socioeconomic status, psychological variables, or health practices. The percentage of days feeling rested was not associated with colds. Conclusion Poorer sleep efficiency and shorter sleep duration in the weeks preceding exposure to a rhinovirus were associated with lower resistance to illness.

Suia, X., J. N. Laditkab, et al. (2008). "Prospective study of cardiorespiratory fitness and depressive symptoms in women and men " Journal of Psychiatric Research. 43 (5): 546-552 [Abstract/Full Text]
Most studies of the relationship between cardiorespiratory fitness (CRF) and depression have been limited to cross-sectional designs. The objective of this study was to follow individuals over time to examine whether those with higher levels of CRF have lower risk of developing depressive symptoms. Participants were 11,258 men and 3085 women enrolled in the Aerobics Center Longitudinal Study in Dallas, TX. All participants completed a maximal treadmill exercise test at baseline (1970-1995) and a follow-up health survey in 1990 and/or 1995. Individuals with a history of a mental disorder, cardiovascular disease, or cancer were excluded. CRF was quantified by exercise test duration, and categorized into age and sex-stratified groups as low (lowest 20%), moderate (middle 40%), or high (upper 40%). Depressive symptoms were assessed using the 20-item Center for Epidemiologic Studies Depression Scale (CES-D). Those who scored 16 or more on the CES-D were considered to have depressive symptoms. After an average of 12 years of follow-up, 282 women and 740 men reported depressive symptoms. After adjusting for age, baseline examination year, and survey response year, the odds of reporting depressive symptoms were 31% lower for men with moderate CRF (odds ratio, OR 0.69; 95% confidence interval, CI 0.56-0.85) and 51% lower for men with high CRF (OR 0.49, CI 0.39-0.60), compared to men with low CRF. Corresponding ORs for women were 0.56 (CI 0.40-0.80) and 0.46 (CI 0.32-0.65). Higher CRF is associated with lower risk of incident depressive symptoms independent of other clinical risk predictors.

Iliffe, S., T. Masud, et al. (2008). "Promotion of exercise in primary care." BMJ 337(dec11_3): a2430-.  [Extract/Full Text
This helpful editorial comments "The health benefits of exercise are so great that it is probably the most important self help treatment available. Regular exercise reduces the risk of cardiovascular and respiratory disease, type 2 diabetes, some cancers, and death from all causes. Regular physical activity and structured exercise can also reduce falls and injuries, and it is a key factor in the prevention and management of osteopenia and osteoporosis. It also promotes mental wellbeing and helps people to manage their weight. Effective promotion of exercise could result in substantial healthcare savings, but this is hampered by our limited knowledge of how to achieve sustained increases in physical activity. The linked study by Lawton and colleagues assesses the effectiveness of an "exercise on prescription" programme in less active women in primary care over two years."  The editorial goes on to discuss these issues.

Brooks, J. H. M. and S. J. Erith (2008). "Warm-up programmes in sport." BMJ 337(dec09_2): a2381-.  [Extract/Full Text
Injuries sustained by participants in team sports place a considerable burden on medical services, and they often disrupt the lives of those injured. Evidence based strategies to prevent injury should therefore be encouraged. Sports teams often perform a warm-up routine with the dual purpose of improving performance and reducing the risk of injury. Although the theory that warming up effectively will reduce the risk of injury makes sense, data from the sports medicine literature are equivocal, and this theory has rarely been proved through randomised control trials. In the linked study, Soligard and colleagues report a cluster randomised controlled trial of an injury prevention programme in young female football players in Norway. A 20 minute warm-up intervention was conducted before training sessions and matches. The warm-up routine consisted of a series of exercises focusing on awareness and neuromuscular control during active movements. The routine is referred to as the "11+" and is a development of the "11" series of exercises devised by the medical department of the international football federation (FIFA). The control group warmed up as usual and did not report using similar exercises to those incorporated in the routine used by the intervention group. Although the primary outcome of injuries to the lower extremity was not significantly different between groups, overall injuries (rate ratio 0.68), overuse injuries (0.47), and severe injuries (0.55) were all significantly lower in the intervention group than in the control group.

Orth-Gomer, K., N. Schneiderman, et al. (2009). "Stress Reduction Prolongs Life in Women With Coronary Disease: The Stockholm Women's Intervention Trial for Coronary Heart Disease (SWITCHD)." Circ Cardiovasc Qual Outcomes 2(1): 25-32.  [Abstract/Full Text
Background-- Psychosocial stress may increase risk and worsen prognosis of coronary heart disease in women. Interventions that counteract women's psychosocial stress have not previously been presented. This study implemented a stress reduction program for women and investigated its ability to improve survival in women coronary patients. Methods and Results-- Two hundred thirty-seven consecutive women patients, aged 75 years or younger, hospitalized for acute myocardial infarction, coronary artery bypass grafting, or percutaneous coronary intervention were randomized to a group-based psychosocial intervention program or usual care. Initiated 4 months after hospitalization, intervention groups of 4 to 8 women met for a total of 20 sessions that were spread over a year. We provided education about risk factors, relaxation training techniques, methods for self-monitoring and cognitive restructuring, with an emphasis on coping with stress exposure from family and work, and self-care and compliance with clinical advice. From randomization until end of follow-up (mean duration, 7.1 years), 25 women (20%) in the usual care and 8 women (7%) in the stress reduction died, yielding an almost 3-fold protective effect of the intervention (odds ratio, 0.33; 95% CI, 0.15 to 0.74; P=0.007). Introducing baseline measures of clinical prognostic factors, including use of aspirin, {beta}-blockers, angiotensin-converting enzyme inhibitors, calcium-channel blockers, and statins into multivariate models confirmed the unadjusted results (P=0.009). Conclusions-- Although mechanisms remain unclear, a group-based psychosocial intervention program for women with coronary heart disease may prolong lives independent of other prognostic factors.


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