Sleep disorders and their impacts on healthy, dependent, and frail older adults.

BACKGROUND: Sleep disorders differ widely in the heterogeneous older adult population. Older adults can be classified into three groups based upon their overall level of disability: healthy, dependent, and frail. Frailty is an emerging concept that denotes older persons at increased risk for poor outcomes.
OBJECTIVE: The aim of this consensus review is to describe the sleep disorders observed in healthy and dependent older adults and to discuss the potential sleep disorders associated with frailty as well as their potential consequences on this weakened population.
METHODS: A review task force was created including neurologists, geriatricians, sleep specialists and geriatric psychiatrists to discuss age related sleep disorders depending on the three categories of older adults. All published studies on sleep in older adults on Ovid Medline were reviewed and 106 articles were selected for the purpose of this consensus.
RESULTS: Many healthy older adults have complains about their sleep such as waking not rested and too early, trouble falling asleep, daytime napping, and multiple nocturnal awakenings. Sleep architecture is modified by age with an increased percentage of time spent in stage one and a decreased percentage spent in stages three and four. Insomnia is frequent and its mechanisms include painful medical conditions, psychological distress, loss of physical activity and iatrogenic influences. Treatments are also involved in older adults' somnolence. The prevalence of primary sleep disorders such as restless legs syndrome, periodic limb movements and sleep disordered breathing increases with age. Potential outcomes relevant to these sleep disorders in old age include mortality, cardiovascular and neurobehavioral co-morbidities. Sleep in dependent older adults such as patients with Alzheimer Disease (AD) is disturbed. The sleep patterns observed in these patients are often similar to those observed in non-demented elderly but alterations are more severe. Nocturnal sleep disruption and daytime sleepiness are the main problems. They are the results of Sleep/wake circadian rhythm disorders, environmental, psychological and iatrogenic factors. They are worsened by other sleep disorders such as sleep disordered breathing. Sleep in frail older adults per se has not yet been formally studied but four axes of investigation should be considered: i) sleep architecture abnormalities, ii) insomnia iii) restless legs syndrome (RLS), iv) sleep disordered breathing.
CONCLUSION: Our knowledge in the field of sleep disorders in older adults has increased in recent years, yet some groups within this heterogeneous population, such as frail older adults, remain to be more thoroughly studied and characterized.