Searching for the brain bases of insomnia.

Insomnia, daytime sleepiness, and napping are all highly prevalent among the elderly, reflecting changes in sleep architecture, sleep efficiency, sleep quality, and circadian sleep-wake cycles. Insomnia is sometimes associated with subjective daytime sleepiness, as well as other clinical and socioeconomic consequences. The daytime sleepiness will at times lead to napping. Although napping is viewed as a common age-related occurrence, little is known about its benefits or consequences. Factors reported to be contributors to daytime napping include sleep-maintenance difficulty and sleep fragmentation with consequent daytime sleepiness, nighttime use of long-acting sedating agents, daytime use of sedating medications, and dementia. However, a correlation between sleep disturbance and daytime napping has not been consistently observed. Whether napping is beneficial, neutral, or detrimental is an important issue, in light of conflicting findings regarding the impact of daytime napping on nighttime sleep and recent reports of an association between napping and adverse clinical outcomes, including increased mortality risk. Further research is needed to determine whether there is a cause-and-effect relationship between napping and insomnia, and between napping and adverse clinical outcomes, and to explore the clinical implications of improving insomnia and reducing daytime napping. Clinical evaluations of hypnotic agents should assess efficacy for both improving insomnia symptoms (particularly sleep-maintenance difficulty, in the case of elderly patients) and reducing daytime sleepiness thatwould lead to inadvertent napping.