Specific areas of the brain were found to be responsible for short pulses versus long-term exposure to light, found Northwestern University researchers. This finding challenges the widely accepted, long-held belief that all light information is relayed through the brain's suprachiasmatic nucleus (SCN), which synchronizes the body's sleep/wake cycles.
While this acute burst of light does make it more difficult to fall back to sleep,reports that it won't interfere with the body's overall circadian rhythms.
Sleep Disturbances In Women
The physical, emotional and hormonal changes that occur in women during puberty, menstrual cycle, pregnancy, and menopause can cause Sleep Disturbances
Advertisement
‘Different pathways process long-term circadian rhythms and short-term exposure to light. ’
Tweet it Now
"Prior to the widespread use of electricity, our exposure to light and darkness occurred in a very predictable pattern," said Northwestern's Tiffany Schmidt, who led the study. "But light has become very cheap. We all have smartphones, and their screens are very bright. We're all getting exposed to light at the wrong times of day. It's becoming more important to understand how these different types of light information are relayed to the brain."
The paper will publish July 23 in the journal eLife. Schmidt is an assistant professor of neurobiology in Northwestern's Weinberg College of Arts and Sciences. The study was carried out in collaboration with the laboratories of Fred Turek, the Charles and Emma Morrison Professor of Neurobiology in Weinberg, and Samer Hattar, section leader at the National Institute of Mental Health.
![Quiz on Obstructive Sleep Apnea]( "Quiz on Obstructive Sleep Apnea")
Do you feel sleepy all day despite sleeping normal hours? One of the possible reasons for this sleepiness could be obstructive sleep apnea. Test your knowledge on obstructive sleep apnea by taking this quiz.
After light enters the eye, specialized neurons called intrinsically photosensitive retinal ganglion cells (ipRGCs) carry the light information to the brain. Before Northwestern's study, researchers widely believed that all light information went through the SCN, a densely packed area in the hypothalamus known as the body's "circadian pacemaker."
"Light information comes into the SCN, and that's what synchronizes all of the body's clocks to the light/dark cycle," Schmidt said. "This one master pacemaker makes sure everything is in sync."
To conduct the study, Schmidt and her team used a genetically modified mouse model that only had ipRGCs projecting to the SCN -- but no other brain regions. Because mice are nocturnal, they fall asleep when exposed to light. The mice in the experiment, however, stayed awake when exposed to short pulses of light at night. The mice's body temperature, which also correlates to sleep, also did not respond to the short-term light.
The mice maintained a normal sleep/wake cycle and normal rhythms in their body temperature, suggesting that their overall circadian rhythms remained intact. This helps explain why one night of restless sleep and smartphone gazing might make a person feel tired the following day but does not have a long-term effect on the body.
"If these two effects -- acute and long-term light exposure -- were driven through the same pathway, then every minor light exposure would run the risk of completely shifting our body's circadian rhythms," Schmidt said.
Now that researchers know that the light-response system follows multiple pathways, Schmidt said more work is needed to map these pathways. For one, it is still unknown what area of the brain is responsible for processing acute light.
After more is known, then researchers might understand how to optimize light exposure to increase alertness in those who need it, such as nurses, shift workers and emergency personnel, while mitigating the harmful effects of a wholesale shift in circadian rhythms.
"Light at the wrong time of day is now recognized as a carcinogen," Schmidt said. "We want people to feel alert while they are exposed to light without getting the health risks that are associated with shifted circadian rhythms, such as diabetes, depression and even cancer."
Source: Eurekalert
Quiz on Obstructive Sleep Apnea
Do you feel sleepy all day despite sleeping normal hours? One of the possible reasons for this sleepiness could be obstructive sleep apnea. Test your knowledge on obstructive sleep apnea by taking this quiz.
Advertisement
After light enters the eye, specialized neurons called intrinsically photosensitive retinal ganglion cells (ipRGCs) carry the light information to the brain. Before Northwestern's study, researchers widely believed that all light information went through the SCN, a densely packed area in the hypothalamus known as the body's "circadian pacemaker."
"Light information comes into the SCN, and that's what synchronizes all of the body's clocks to the light/dark cycle," Schmidt said. "This one master pacemaker makes sure everything is in sync."
To conduct the study, Schmidt and her team used a genetically modified mouse model that only had ipRGCs projecting to the SCN -- but no other brain regions. Because mice are nocturnal, they fall asleep when exposed to light. The mice in the experiment, however, stayed awake when exposed to short pulses of light at night. The mice's body temperature, which also correlates to sleep, also did not respond to the short-term light.
The mice maintained a normal sleep/wake cycle and normal rhythms in their body temperature, suggesting that their overall circadian rhythms remained intact. This helps explain why one night of restless sleep and smartphone gazing might make a person feel tired the following day but does not have a long-term effect on the body.
"If these two effects -- acute and long-term light exposure -- were driven through the same pathway, then every minor light exposure would run the risk of completely shifting our body's circadian rhythms," Schmidt said.
Now that researchers know that the light-response system follows multiple pathways, Schmidt said more work is needed to map these pathways. For one, it is still unknown what area of the brain is responsible for processing acute light.
After more is known, then researchers might understand how to optimize light exposure to increase alertness in those who need it, such as nurses, shift workers and emergency personnel, while mitigating the harmful effects of a wholesale shift in circadian rhythms.
"Light at the wrong time of day is now recognized as a carcinogen," Schmidt said. "We want people to feel alert while they are exposed to light without getting the health risks that are associated with shifted circadian rhythms, such as diabetes, depression and even cancer."
Source: Eurekalert
Epworth Sleepiness Scale
Measure your daytime sleepiness using this simple interactive tool, based on Epworth Sleepiness disorder Scale. Excessive Daytime Sleepiness is a type of hypersomnia characterized by persistent sleepiness and lack of energy.
Advertisement
 Foods Inducing Sound SleepInsomnia has become a serious health problem and people tend to depend on quick yet risky solutions to get rid of it. But here is the list of nature's best sleep inducing foods right in our kitchen. | Advertisement
|
Advertisement
Recommended Reading
Latest Research News
Decoding the eight factors affecting Black adults' life expectancy.
Sobering truth about foot travel in the United States emerges from international statistics, highlighting the prevalence of walking on the Blacksburg campus.
Unveiling a hidden mechanism, proteins within brain cells exhibit newfound abilities at synapses, reinforcing Darwin's theory of adaptation and diversity in the natural world.
Combining micro-needling and cupping, two emerging and alternative techniques, in an experimental study reveals a potential synergy for skin rejuvenation.
Despite a decline in COVID-19 cases, the World Health Organisation (WHO) raises global concerns by warning of an "inevitable" next pandemic known as "Disease X".