Up to 40% of American’s are sleep deprived. Sleep deprivation has been associated with obesity, hypertension, an increase in inflammatory factors, slow glucose metabolism, impaired insulin sensitivity (both leading to diabetes), depression and elevation of stress hormones such as cortisol, all of which increase the risk for cardiovascular disease (CVD). And we all know about the deleterious effects of inadequate physical activity (both direct and indirect though obesity) on cardiovascular risk factors. So the question is: if we exercise but still don’t find the time to get adequate sleep, does the exercise still work to ward off coronary vascular disease?
An answer to this query was provided in the April issue of the journal Menopause. The article was titled “Association of leisure physical activity and sleep with cardiovascular risk factors in postmenopausal women”. The authors analyzed 393 participants of the Women on the Move Though Activity and Nutrition Study. (You guessed it, the acronym is WOMAN). This was a 5-year randomized clinical trial designed to test whether an intensive non-medication lifestyle intervention would reduce measures of cardiovascular risk factors.
The women’s physical activity was measured in metabolic equivalents and took into account 39 common, non work (leisure) activities. The women designated as high in leisure time activity were those who had 11.8 or more MET hours per week which was the equivalent of 177 minutes of brisk walking. (That, in case you haven’t done the calculation, comes to a little more than 25 minutes a day.)
The women’s sleep was assessed at 48 months though a sleep questionnaire (the Pittsburgh Sleep Quality Index or PSQI…it seems that the researchers in Pittsburg have been particularly active in sleep science.) The women were asked about sleep quality, duration, how long it took them to fall asleep, sleep disturbance (for example a companion’s snoring or their own), use of sleep medications, daytime drowsiness and habitual sleep efficiency. Based on their subsequent PSQI, they were given a global score ranging from 0 to 21. A high score indicated poor sleep quality, and scores higher than 5 meant significant sleep disturbance. The National Sleep Foundation recommends adults sleep 7 to 9 hours a night. In this analysis, appropriate sleep time was defined as 7 or more hours a night. Therefore, those women who were classified as good sleepers had a PSQI score of 5 or less and slept at least 7 hours a night. The poor sleepers had a higher PSQI score and slept less than those 7 hours. (I hope you are following this; perhaps you needed more sleep to do so…)
Women in the high-active group had more favorable body mass indexes or BMI’s (think weight for height), narrower waists, lower blood pressure, less low-density lipoprotein (the bad cholesterol), less total body fat, lower insulin and glucose levels than did the women in the low-active group regardless of sleep quality. Even when women in the high active group with poor sleep quality where compared to less active women but who had good sleep quality they still had a lower BMI, waist circumference, and total body fat and insulin level.
Bottom line: Exercise may be more important than sleep when it comes to lowering risk factors for coronary heart disease in postmenopausal women. The authors put it in a slightly more refined and scientific way: “The combined associations of leisure-time physical activity and sleep suggest that cardiovascular risk factors are more favorable in highly active women relative to less active women regardless of sleep.” I’m going out to take a hike, but I also plan to get to bed early, at least tonight!