Sleep and circadian rhythm disruption (SCRD) has long been linked to increased risk for metabolic disease, obesity, diabetes, and cancer. Now, emerging data are showing that SCRD’s adverse effects extend to our neurologic and mental health as well.

Mental illness and neurologic diseases have well-established associations with SCRD. Major depression goes hand-in-hand with insomnia. Patients with bipolar disorder can have manic episodes provoked by seasonal changes and long-distance travel. The late afternoon/early evening agitation that patients with Alzheimer disease commonly experience (also known as “sundowning”) is one of the key contributors to institutionalization.

However, what has changed in recent years is the rapidly evolving hypothesis that such disturbances may foreground, as well as follow, these conditions, according to Michael J. McCarthy, MD, PhD, associate professor in the department of psychiatry at the University of California San Diego.