Introduction
An increase in the population of the elderly and its associated costs in various societies are issues that has always been considered in recent decades (1, 2). Accordingly, it is necessary to allocate a significant portion of the health and medical resources of any community to the elderly. The consequences of aging due to poor life style have been proven in the form of destructive changes in the physiological, cognitive and psychmotor functions in the elderly population. These changes include changes in the central nervous system, and in particular the brain, which affects most parts of the body and can make the elderly vulnerable to diseases such as Alzheimer’s, Parkinson’s, Multiple sclrosis and other diseases (1). As the human brain responds to the environmental factors easily and creates structural and functional changes that are called neurodegenerative shapes, intervening proper strategies are highly recommended (3). Based on research evidences, executive functions such as information processing, reaction time, attention capacity are impaired in the elderly following aging process. In this regard, sleeping as part of a daily life to recycle, rejuvenate and restore the functioning of the nervous and physiological system of the body is of utmost importance which contributes to the regulation of biological rhythm and helps to improve mental and physiological regeneration. Insomnia is the most common sleep disorder in aged populations that has been extensively investiated . The patients with sleeping disorders are characterized by inability to sleep and lack of effective sleep. A previous study found that 30.7% of the elderly were suffered from sleep disorders (4).
Recently, it has been hypothesized that vitamin D plays an important role in controlling sleep in the brain stem, and it has been argued that vitamin D deficiency is the epidemic reason of sleep disorder (5, 6). On the other hand, the beneficial role of exercise in improving the quality of sleep has always been of interest for scientists (1, 4). The effectiveness of organized exercise protocols such as weight loss exercises (7), strength training (8), aerobic exercises (1, 9) and aquatic excercises on the quality of sleep have been proven. Spiegel et al. (2005) concluded that sleep disorders for several consecutive days increased the resistance of pripheral tissues to insulin, impaired glucose tolerance, increased hunger, and food intake which were somewhat different stimulants to disturb the hormonal balance in the body (12). It has been shown that the lower the quality of sleep, the more stressful hormones are produced in the body (13). The prevention of sleep disorders, due to the importance in various functions of the body, is one of the issues that has a high value of research and can affect the fuctions of various organs in the body (13, 14). With respect to the importance of lifestyle in the elderly, proper life style and physical activity and having a suitable sleep pattern are among the factors that can lead to successful aging. Considering the current prevalence of sleep disturbances, the reduction in sleep time and the decrease of physical activity in the elderly, the aim of the present study was to investigate the effect of an aerobic training protocol along with vitamin D supplementation on neurocognitive functions of elderly women with sleep disorders.
In view of the above consideration, it was hypothesized that combined aerobic training with vitamin D supplementation could improve the neurocognitive functions of elderly women with sleep disorders.