Ultrashort Light Pulses as a Personalized Countermeasure for Circadian Desynchrony
Abstract
We are a 24-hour society. We require both civilians and members of the Armed Services to work hours to which their bodies and brains cannot adapt. Our ability to sleep at night and be awake and alert during the day is governed by an internal timer -- the circadian clock. This clock synchronizes the function of all manner of activity in the brain and body, including that of the heart, immune system, metabolism, memory function, and hormone release. The circadian clock itself remains aligned to the external day through regular exposure to light and dark. When individuals work at night or rapidly travel across multiple time zones, the circadian clock becomes misaligned with a person s desired schedule, leading to difficulty sleeping, poor physical and mental performance, and long-term health consequences including an increased risk for cancer. In addition to work- and travel-associated misalignment of the circadian clock with people s behavior, approximately 1 out of every 20 people have a naturally occurring tendency to go to sleep at an unusual time relative to their desired bedtime. These are known as the circadian clock-associated sleep disorders of Advanced Sleep and Delayed Sleep. While there is nothing intrinsically wrong about, for example, sleeping from 3 a.m. - 11 a.m., it is difficult to adopt that schedule and simultaneously conform to the expectations and requirements (e.g., school, work) of society. These types of circadian clock-associated disruptions can be treated with properly timed exposure to bright light. While in a laboratory, bright light exposure on a daily basis is an efficacious countermeasure, in the real world, this therapy is ineffective as it requires people to sit in front of bright lights usually for more than 1 hour and often during a time when they would normally be asleep. This "phototherapy" is tedious, disruptive, and must occur on a daily basis in order to reap its rewards. New research from my laboratory has uncovered a novel way in which these circadian clock-based disruptions can be treated. Instead of having people change their sleep schedule and sit in front of bright lights for hours at a time, we are able to give a sequence of light flashes during sleep that move the circadian system into a desired alignment. These light flashes do not disrupt sleep, and they can actually generate larger changes in the timing of the circadian clock than continuous light. These larger changes may allow us to evoke the large changes in circadian timing that are necessary to rapidly adapt people to shift work and long-distance jet travel. Using a series of in-laboratory clinical trials that are aimed at optimizing the effects of the sequence of light flashes, we intend to show that we can rapidly adapt internal circadian time to any desired schedule. This therapy can be done while people sleep, resulting in a simple, inexpensive, passive, customizable treatment. Instead of taking days or weeks to adjust to a new time zone, it could be done in a single night. Instead of being unable to enjoy family time during days off, shift workers will be able to be alert on the job and at home. Service members will be able to rapidly adapt to new schedules and new time zones. Patients will be able to choose their sleep schedule. This therapy will make invaluable changes in the lives of millions of patients with Delayed and Advanced Sleep disorder and transform the lives of the more than 15 million Americans who work shifted schedules and the countless others who suffer from the deleterious effects of jet travel. This project specifically addresses two of the Fiscal Year 2015 Peer Reviewed Medical Research Program Topic Areas: (1) non-pharmacological treatments for sleep disorders and (2) how to prevent/reduce sleep disorders that are associated with long aeromedical evacuation flights for both clinical team members and patients.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 31, 2017
- Source ID
- W81XWH1610223
Entities
People
- Jamie M. Zeitzer
Organizations
- Palo Alto Veterans Institute for Research
- United States Army