Too much light at night ''is bad for sleep routines''
Chronic exposure to even dim levels of light at night can have a significant unwanted effect on the ability to get a sound night's sleep and a growing risk of depression, new research has shown.
A study carried out by scientists at Ohio State University revealed that in animals, being forced to sleep with a low level of light as opposed to complete darkness led to the introduction of depressive symptoms in subjects, such as lacking energy and motivation.
The research has now been linked to rising levels of depression seen in the human population over the last 50 years.
Researchers connected the growing popularity of PCs, televisions and other electronic devices in the bedroom as a key contributor to individuals sleeping with low levels of light in the room.
The findings were based on two tests involving hamsters, whereby half of subjects were exposed to a standard day-night cycle of lighting - 16 hours of light and eight hours of complete darkness - while a second group of animals had 16 hours of standard light followed by eight hours of dim light conditions.
At the end of the four-week trial, the group exposed to chronic dim light were found to be less interested in basic actions, such as drinking, eating and a general lethargy in comparison to their control group counterparts.
However, the study highlighted how these increased risk factors could be counteracted by simply removing these unwanted night-time stimuli and that within a few weeks of returning to a proper day-night light cycle, all symptoms of depressive behaviour disappeared in animal subjects.
Tracy Bedrosian, lead author of the study and doctoral student in neuroscience at the university, said: "The good news is that people who stay up late in front of the television and computer may be able to undo some of the harmful effects just by going back to a regular light-dark cycle and minimising their exposure to artificial light at night. That's what the results we found in hamsters would suggest."
Correlation between animal subjects and the human population are possible due to the myriad studies that have been carried concerning depression in people and the risk factors for the development of this condition, with Ms Bedrosian noting: "The results we found in hamsters are consistent with what we know about depression in humans."
Following the experiment, the animals were humanely euthanised and an area of their brain known as the hippocampus was studied. In those animals exposed to dim light at night higher levels of a protein known to be associated with tumour necrosis factor were discovered, highlighting the impact of these protein levels on the brain of these animals.
The studies were published in the journal Molecular Psychiatry.
As a result, people wishing to improve their mood and become less likely to develop depressive symptoms should ensure they sleep in complete darkness and switch off electronic devices that could be keeping them awake at night.
Marianne Davey, director of the British Snoring & Sleep Apnoea Association, recently argued individuals should pay more attention to getting the recommended amount of deep sleep, as it is during these periods that the body releases hormones that allow cells and tissues to repair themselves and grow.
As such, those who fail to achieve the recommended seven to eight hours of sleep per night could begin to suffer from a range of ailments.
She commented: "Brain function suffers most from lack of sleep as it reduces the capacity for decision making, impairs judgement, affects memory and concentration.
"Physical consequences include headache and gastrointestinal problems, and there is increasing evidence that there is a link between lack of sleep and a higher risk of major illnesses such as heart disease, diabetes, some cancers and obesity."
Posted by Michael Ewing