The Scientist unveiled the Top 10 Innovations of 2011, and coming in at number eight was the Dimesimeter, a circadian light and activity sensor developed by the Lighting Research Center (LRC) at Rensselaer Polytechnic Institute through funding from the National Institute on Aging (NIA).
For the fourth consecutive year, The Scientist invited members of the life science community to submit descriptions of exciting tools that made an impact in research, according to the magazine’s official announcement. More than 65 entries were reviewed by a panel of experts who were asked to evaluate the technologies and come up with the top ten innovations of 2011. The judges on the panel were neurobiologist Björn Brembs of the Freie Universität in Berlin, neuronal cell biologist Michael Kiebler of Medical University of Vienna’s Center for Brain Research, Biovista president and cofounder Aris Persidis, and Pacific Northwest National Laboratory biologist H. Steven Wiley.
The Dimesimeter is calibrated in terms of the spectral sensitivities of the visual and the circadian systems, as the circadian system is much more sensitive to short-wavelength (“blue”) light. Commercially available light measurement devices are only calibrated to measure light for vision.
“Biology is driven by circadian rhythms at every level, and light is the main stimulus for synchronizing the circadian system to the solar day. By quantifying an individual’s light/dark exposure pattern, we can prescribe ‘light treatments’ promoting circadian entrainment, thereby improving health and well-being,” explained Mariana Figueiro, Rensselaer associate professor, director of the Light and Health Program at LRC, and principal investigator on the project.
Growing evidence indicates that circadian disruption by irregular light/dark patterns is associated with reduced quality of life and increased risk of disease. The Dimesimeter system—a combination of light monitoring and therapy prediction—has the potential to positively affect the lives of millions who suffer from circadian rhythm sleep disorders, including persons with Alzheimer’s disease.
Persons with Alzheimer’s disease and related dementias (ADRD) suffer from erratic sleep cycles, nocturnal wandering, and associated daytime irritability, which can make it difficult for family caregivers to cope and maintain a safe, at-home environment. These sleep disturbances are due, in part, to the absence of daily, robust light/dark pattern exposures, explained Figueiro.
The LRC has studied the implications of light/dark exposure on the circadian system both in the laboratory and in the field, including studies with ADRD sufferers. Most recently, through the NIA award (#R01AG034157), the LRC is collaborating with clinicians at Case Western Reserve University and Louis Stokes Cleveland VA Medical Center in Cleveland, Ohio, to test the effectiveness of a lighting intervention on sleep efficiency in persons with ADRD. The lighting intervention is designed to effectively improve their rest/activity patterns and increase their sleep efficiency. These study subjects are currently wearing the Dimesimeter to determine their light/dark and activity/rest patterns before and after the lighting intervention, which was designed to maximally affect the circadian system during daytime hours.
How the Dimesimeter works
Light/dark patterns on the retina, the photosensitive part of the eye, can synchronize our internal biological clock with the 24-hour solar day, thereby regulating the timing of our sleep and other daily biological cycles, called circadian rhythms. In the absence of this environmental cue, circadian rhythms will free run and consolidation of rest/activity rhythms will be lost.
The Dimesimeter is an unobtrusive, data-logging device (only 2-centimeters in diameter) that records an individual’s light and activity levels continuously over many days. It’s fitted with a pin for attaching to shirt collars, lapels, hats, wristbands, or glasses. This flexibility increases the chances fo complinace when working with various populations, including those with ADRD.
The Dimesimeter enables researchers to examine light/dark and activity/rest patterns in those experiencing circadian sleep disorders, such as Alzheimer’s disease patients. The Dimesimeter also provides an objective measure of daily and nightly light exposure levels. Data are readily downloaded and can interface with personal computing equipment such as a laptop. Once downloaded, the logged data are processed to calculate a cross-correlation of the activity/rest and light/dark exposure data.
“The cross-correlation of the logged data, called phasor analysis, is an integral component of the Dimesimeter system and yields quantitative information about the individual’s degree of circadian entrainment. The data are then automatically formatted into easy-to-read graphs defining the person’s current circadian entrainment/disruption status, from which key diagnostic and prescriptive decisions can be made,” explained Andrew Bierman, Rensselaer adjunct assistant professor, LRC senior research scientist, and project team member.
No other system exists to both accurately measure human circadian light/dark exposure and activity/rest patterns over several days, allowing researchers to collect ecological data on various populations who suffer from circadian sleep disorders, such as older adults, shift workers, adolescents, and sufferers from seasonal depression, and better assess behavioral circadian entrainment/disruption, according to the LRC.
The Dimesimeter can be used to predict the optimum timing of the light therapy necessary to resynchronize the circadian phase with the solar day. Such treatments could range from standing outside for 15 minutes to sitting in front of a light box fitted with blue LEDs for a prescribed amount of time.
“This new measurement and analysis technique allows for future studies that can then serve as the next logical step in understanding the impact of circadian disruption on human health, complementing the pioneering epidemiological studies that have raised collective concern for how circadian disruption might impact human health,” said Mark Rea, Rensselaer professor and LRC director.
See the complete list of The Scientist Top 10 Innovations of 2011 here.
Learn more about the Dimesimeter.
Watch a short video about the Dimesimeter
About the National Institute on Aging (NIA)
NIA, one of the 27 Institutes and Centers of the National Institutes of Health, leads the federal government in conducting and supporting research on aging and the health and well-being of older people. The Institute seeks to understand the nature of aging and the aging process, and diseases and conditions associated with growing older, in order to extend the healthy, active years of life. In 1974, Congress granted authority to form NIA to provide leadership in aging research, training, health information dissemination, and other programs relevant to aging and older people. Subsequent amendments to this legislation designated NIA as the primary Federal agency on Alzheimer’s disease research. For more information, please visit www.nia.nih.gov.