The Effect Of Tai Chi Exercise On Older Adults’ Sleep And Sleep-related Cognitive Function

Sleep disorders are prevalent in older adults and can cause a variety of symptoms,such as daytime dysfunction,daytime sleepiness,mood disorders,psychiatric disorders,the function of cognitive and the quality of life declined.Sleep not only has physical function but also has cognitive function.Of these,the consolidation effect of sleep on memory has been confirmed by numerous empirical studies.The active system consolidation hypothesis posits that newly encoded memories will be reactivated during sleep and transferred from the hippocampus to neocortex for long-term storage.Improving sleep not only improves sleep itself in older adults,but also plays a crucial role in the improvement of sleep-related cognitive function.Previous studies have shown the effects of aerobic exercise on sleep and cognitive improvement in older people.Tai Chi,as a low to moderate intensity form exercise,is easy to practice,low cost and safe,making it more suitable for long-term exercise in older adults.Previous studies have mainly isolated the improvement of Tai Chi exercise on older adults’ sleep and cognitive function,and most of the sleep indicators are subjective sleep questionnaires,with little evidence from objective sleep.In this study,we will explore the improvement of subjective sleep,objective sleep and sleep-related cognitive function in community older adults by eight weeks Tai Chi exercise,and to explain this mechanism based on previous studies.In experiment 1,the influence of Tai Chi exercise on subjective sleep of the older adults was investigated.The subjective sleep was measured by the Pittsburgh Sleep Quality Index scale and its seven sub-dimensions and insomnia Severity Index scale.After eight weeks of Tai Chi exercise,the results showed that the experimental group’s subjective sleep has significant improved on insomnia Severity Index scale and daytime dysfunction scores.The finding suggests that in addition to the daily activities,the regular participation of Tai Chi in older adults may provide the protective effects in subjective sleep.In experiment 2,the influence of Tai Chi exercise on objective sleep of the older adults was investigated.Objective sleep indicators were collected from Actigraph for one week before exercise,in the middle of exercise and after exercise.For total in bedtime(TIB),Tai Chi started to have an effect on improve TIB for older adults at midexercise,with a significant decrease in TIB in the experimental group at four weeks of the Tai Chi exercise,and this effect continued steadily until the end of Tai Chi exercise.At the same time,the Tai Chi exercise significantly reduced the sleep of latency(SOL)of the experimental group,evidenced by a significant decrease in SOL at the end of the exercise compared to the mid-exercise.This result also shows that the effect of the Tai Chi exercise on the improvement of objective sleep quality in older adults.Experiment 3 explored the effects of Tai Chi exercise on the sleep-related cognitive function of older adults and its EEG mechanisms.The results found that after the Tai Chi exercise,experimental group performed better on digit span memory(original order),picture memory and location memory tasks.In addition,multiple linear regression was assessed to investigate the relationship between subjective and objective sleep and cognition,we found that the baseline of subjective and objective sleep can significantly predict the baseline performance of picture memory,with PSQI-sleep quality and PSQI-daytime dysfunction significantly predicting picture memory performance.Meanwhile,in order to explore the EEG mechanism of cognitive changes after the Tai Chi exercise,we analyzed the correlation between the significant changed cognitive variables(original digit span memory,picture memory and location memory:post-pre value)with the sleep variables changes(spindle and slow oscillation: post-pre value).The results revealed that the improvement of picture memory in experimental group was significantly correlated with the change of spindle duration and spindle oscillation.This result is consistent with our expectation that Tai Chi can improve cognition performance in older adults and this cognitive change is related to the features of the spindle.In summary,Tai Chi as a traditional aerobic exercise,which can improve subjective sleep,objective sleep and cognition function in older adults,and this improvement is affected by the features of the spindle.The present study demonstrated that regular practice in Tai Chi may provide a protective effect on the subjective and objective sleep of older people,effectively alleviating sleep disturbances in older people,this reducing the pressure on sleep clinics.