Author:

Abstract:

Both physical activity and sleep have been identified as crucial determinants of healthy ageing. However, as people age, they become less physically active and more sedentary. Sleep quantity and sleep quality also tend to decline with ageing, resulting in one in two older adults suffering from sleep problems. Even if the decline in sleep does not result in a diagnosed sleep problem, it has far reaching consequences for an individuals' health and wellbeing. Sleep problems are predominantly treated by means of sleep medications, but these are not always safe to use in the long run. Lifestyle interventions, behavioural change and other non-pharmaceutical treatment options are therefore the preferred choice for maintaining optimal sleep and for the management of sleep problems. Regular physical activity is one of these options. This PhD research aims to progress the knowledge about the relation between physical activity and sleep in older adults by 1) systematically reviewing the literature on effects of physical activity programs on sleep in older adults; 2) examining associations of time reallocations between sedentary behaviour and physical activity with sleep; and 3) evaluating the effects of a real-life lifestyle program 'Lekker Actief' on physical activity and sleep; and examining associations between changes in physical activity and sleep. From the results of the literature study described in Chapter two it can be concluded that physical activity programs in more controlled settings do positively affect sleep outcomes in generally healthy older adults. More specifically, moderate intensity exercise programs, with a frequency of three times per week and a duration of twelve weeks up to six months that include a combination of types of exercises, positively affect sleep quality, sleep latency, sleep disturbances, wake time after sleep onset, sleep duration and sleep efficiency. The empirical studies are described in Chapters three and four. The associations of time reallocations between sedentary behaviour and physical activity with sleep are examined in a cross-sectional study among 439 adults aged 55+ years (Chapter three). There are no positive associations between time reallocations and sleep. However, replacing sedentary behaviour to light intensity physical activity is associated with decreased sleep efficiency. The effect of the 'Lekker Actief' program is examined in a controlled intervention study among 357 adults aged 55+ years (Chapter four). This real-life lifestyle program is effective in increasing physical activity by almost 20 minutes a day. However, the program does not have an effect on sleep. Furthermore, although changes in physical activity are associated with sleep, the associations are small and not clinically relevant. There are several underlying biological mechanisms for a positive relation between physical activity and sleep. In addition, the findings from our literature study indicate that physical activity programs can improve sleep outcomes in controlled settings. Although a positive effect of physical activity on sleep could not be confirmed in our empirical studies in a real-life setting, the biological mechanisms and findings from the literature do provide support for physical activity as part of non-pharmaceutical strategies to optimize sleep and prevent sleep problems. More research is therefore needed, taking our recommendations for future research into account, to further clarify the relation between physical activity and sleep in older adults.