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Wednesday, August 10, 2016

Plenty of Daytime Light May Reduce Effects of Blue Light Screens on Sleep

Sleep is important to all of us, whether you have Parkinson's or not.

NEUROSCIENCE NEWS
Summary: According to researchers, daytime light exposure may help to combat the negative effect blue light exposure has on sleep.
Source: Uppsala University.

Our results could suggest that light exposure during the day, e.g. by means of outdoor activities or light interventions in offices, may help combat sleep disturbances associated with evening blue light stimulation.’ NeuroscienceNews.com image is for illustrative purposes only.


The use of smartphones and tablet computers during evening hours has previously been associated with sleep disturbances in humans. A new study from Uppsala University now shows that daytime light exposure may be a promising means to combat sleep disturbances associated with evening use of electronic devices. The findings are published in the scientific journal Sleep Medicine.

The use of blue light emitting devices during evening hours has been shown to interfere with sleep in humans. In a new study from Uppsala University involving 14 young females and males, neuroscientists Christian Benedict and Frida Rångtell sought to investigate the effects of evening reading on a tablet computer on sleep following daytime bright light exposure.

‘Our main finding was that following daytime bright light exposure, evening use of a self-luminous tablet for two hours did not affect sleep in young healthy students’, says Frida Rångtell, first author and PhD student at the Department of Neuroscience at Uppsala University.

Our results could suggest that light exposure during the day, e.g. by means of outdoor activities or light interventions in offices, may help combat sleep disturbances associated with evening blue light stimulation. Even if not examined in our study, it must however be kept in mind that utilizing electronic devices for the sake of checking your work e-mails or social network accounts before snoozing may lead to sleep disturbances as a result of emotional arousal’, says senior author Christian Benedict, associate professor at the Department of Neuroscience.

Abstract
Two hours of evening reading on a self-luminous tablet vs. reading a physical book does not alter sleep after daytime bright light exposure
Background

The use of electronical devices emitting blue light during evening hours has been associated with sleep disturbances in humans, possibly due to the blue light-mediated suppression of the sleep-promoting hormone melatonin. However, experimental results have been mixed. The present study therefore sought to investigate if reading on a self-luminous tablet during evening hours would alter sleepiness, melatonin secretion, nocturnal sleep, as well as electroencephalographic power spectral density during early slow-wave sleep.


Methods
Following a constant bright light exposure over 6.5 hours (~569 lux), 14 participants (6 females) read a novel either on a tablet or as physical book for 2 hours (21:00-23:00). Evening concentrations of saliva melatonin were repeatedly measured. Sleep (23:15-07:15) was recorded by polysomnography. Sleepiness was assessed before and after nocturnal sleep. About one week later, experiments were repeated yet participants who had read the novel on a tablet in the first experimental session continued reading the same novel in the physical book, and vice versa.


Results
There were no differences in sleep parameters and pre-sleep saliva melatonin levels between the tablet reading and physical book reading conditions.


Conclusions
Bright light exposure during daytime has previously been shown to abolish the inhibitory effects of evening light stimulus on melatonin secretion. Our results could therefore suggest that exposure to bright light during the day – as in the present study – may help combat sleep disturbances associated with the evening use of electronical devices emitting blue light. However, this needs to be validated by future studies with larger sample populations.

“Two hours of evening reading on a self-luminous tablet vs. reading a physical book does not alter sleep after daytime bright light exposure” by Frida H. Rångtell, Emelie Ekstrand, Linnea Rapp, Anna Lagermalm, Lisanne Liethof, Marcela Olaya Búcaro, David Lingfors, Jan-Erik Broman, Helgi B. Schiöth, and Christian Benedict in Sleep Medicine. Published online July 25 2016 doi:10.1016/j.sleep.2016.06.016

http://neurosciencenews.com/daytime-light-blue-screen-sleep-4817/

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