Daily rhythms shape our inner biology as well as our behavior and mental states. These rhythms occur within our individual cells, keeping track of time of day even when those cells are isolated in a petri dish. How do all these cellular rhythms coordinate together?

Light can sync our inner clocks to the sun cycles. Light has powerful effects through direct inputs from cells in the eye to cells in the brain. The suprachiasmatic nucleus in the brain responds to light inputs and coordinates multiple body clocks.

Age and disease can weaken this delicate system. Loss of inner rhythm coordination can worsen disease. We have found that exercise helps restore aged circadian rhythms by altering responses to light and impacting neural circuits.

We are better understanding how chronic disruptions can alter the brain clock and how the body organs can lose their sync with the sun cycles following chronic circadian disruptions.

These studies can impact treatments for Alzheimer’s Disease. We are conducting research now that could potentially help slow early progression of Alzheimer’s dementia.


More reading about our research on

A recent article in the Grecourt Gate about our research on light.

Our efforts to develop an animal model for the study of fatigue highlighted in the Multiple Sclerosis Discovery Forum 

Mice exhibit fatigue in a number of ways, including diminished physical activity on the running wheel. Image by Cynthia McKelvey.


My full CV is here:  M Harrington CV 2023

My Bibliography NCBI: