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2019 Alzheimer's Association Research Grant (AARG)

Circadian Rhythm, Sleep, and Brain in Aging

How can differences in the sleep cycle directly impact brain health and function?

Chooza Moon, Ph.D.
University of Iowa
Iowa City, IA - United States


Circadian rhythms are natural biological changes that occur over an approximately twenty-four hour cycle, which is often called the sleep-wake cycle. These rhythms usually respond to the amount of light and darkness in an environment, and they involve daily patterns of sleeping, eating and other activities. Disruptions to circadian rhythms can alter people’s ability to get proper sleep. More than 50% of individuals with dementia experience sleep disruptions or poor sleep patterns that precede cognitive impairment by several years Past studies suggest that, sleep loss may reduce brain function by hindering the ability of brain cells to communicate with each other or by damaging certain brain structures. Dr. Chooza Moon plans to further explore the relationship between circadian rhythms and altered brain functions in older adults.

Research Plan

Dr. Moon and colleagues will study how differences in circadian rhythms directly impact key aspects of brain structure and function. To conduct their study, the researchers will collect brain scans, biological markers related to circadian rhythm and sleep data from 40 middle-aged to older adults (ages ranging from 55-90). The researchers will analyze this data to determine which individuals have a circadian rhythm that enables them to get to bed earlier or sleep longer per night, and those that have a circadian rhythm resulting in delayed sleep or reduced sleep hours. Dr. Moon will then compare how these different sleep cycles affect (1) the overall volume of a brain region vital for learning and memory, (2) the health of the brain’s wiring system between nerve cells, (3) the ability of brain cells to communicate with each other, and (4) the overall cognitive ability of the participants.


The study results could help clarify how circadian rhythms may impact the way our brain operates. These results could also help design sleep-related interventions that could slow or prevent the onset of Alzheimer’s disease.

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