Web address:
http://www.sciencedaily.com/releases/2011/01/
110113082716.htm
Room Light Before Bedtime May Impact Sleep Quality, Blood Pressure and Diabetes
Risk
ScienceDaily (Jan. 14, 2011) According to a recent study accepted for
publication in The Endocrine Society's Journal of Clinical Endocrinology &
Metabolism (JCEM), exposure to electrical light between dusk and bedtime
strongly suppresses melatonin levels and may impact physiologic processes
regulated by melatonin signaling, such as sleepiness, thermoregulation, blood
pressure and glucose homeostasis.
Melatonin is a hormone produced at night by the pineal gland in the brain. In
addition to its role in regulating the sleep-wake cycle, melatonin has been
shown to lower blood pressure and body temperature and has also been explored
as a treatment option for insomnia, hypertension and cancer. In modern society,
people are routinely exposed to electrical lighting during evening hours to
partake in work, recreational and social activities. This study sought to
understand whether exposure to room light in the late evening may inhibit
melatonin production.
"On a daily basis, millions of people choose to keep the lights on prior to
bedtime and during the usual hours of sleep," said Joshua Gooley, PhD, of
Brigham and Women's Hospital and Harvard Medical School in Boston, Mass. and
lead author of the study. "Our study shows that this exposure to indoor light
has a strong suppressive effect on the hormone melatonin. This could, in turn,
have effects on sleep quality and the body's ability to regulate body
temperature, blood pressure and glucose levels."
In this study, researchers evaluated 116 healthy volunteers aged 18-30 years
who were exposed to room light or dim light in the eight hours preceding
bedtime for five consecutive days. An intravenous catheter was inserted into
the forearms of study participants for continuous collection of blood plasma
every 30-60 minutes for melatonin measurements. Results showed exposure to room
light before bedtime shortened melatonin duration by about 90 minutes when
compared to dim light exposure. Furthermore, exposure to room light during the
usual hours of sleep suppressed melatonin by greater than 50 percent.
"Given that chronic light suppression of melatonin has been hypothesized to
increase relative risk for some types of cancer and that melatonin receptor
genes have been linked to type 2 diabetes, our findings could have important
health implications for shift workers who are exposed to indoor light at night
over the course of many years," said Gooley. "Further research is still needed
to both substantiate melatonin suppression as a significant risk factor for
breast cancer and determine the mechanisms by which melatonin regulates glucose
metabolism."
Other researchers working on the study include: Kyle Chamberlain of the
University of Surrey in the United Kingdom; and Kurt Smith, Sat Bir Khalsa,
Shantha Rajaratnam, Eliza Van Reen, Jamie Zeitzer, Charles Czeisler and Steven
Lockley of Brigham and Women's Hospital and Harvard Medical School in Boston,
Mass.
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Story Source:
The above story is reprinted (with editorial adaptations by ScienceDaily
staff) from materials provided by The Endocrine Society, via EurekAlert!, a
service of AAAS.
Journal Reference:
1. Joshua Gooley et al. Exposure to room light prior to bedtime suppresses
melatonin onset and shortens melatonin duration in humans. JCEM, March 2011
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The Endocrine Society (2011, January 14). Room light before bedtime may impact
sleep quality, blood pressure and diabetes risk. ScienceDaily. Retrieved
January 18, 2011, from http://www.sciencedaily.com
/releases/2011/01/110113082716.htm
Note: If no author is given, the source is cited instead.
Disclaimer: This article is not intended to provide medical advice, diagnosis
or treatment. Views expressed here do not necessarily reflect those of
ScienceDaily or its staff.
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