World Bulletin / News Desk
Sitting in front of a computer or TV screen late into the night or leaving it on when you fall asleep could increase your chances of becoming depressed, according to a study by U.S. scientists.
The study, by a team of neuroscientists at Ohio State University Medical Center partly funded by the U.S. Department of Defense, will give screen-addicted night owls pause for thought.
The researchers - who exposed hamsters to dim light at night and picked up changes in behaviour and the brain that bore striking similarities to symptoms in depressed people - said a surge in exposure to artificial light at night in the last 50 years had coincided with rising rates of depression, particularly among women, who are twice as prone as men.
"The results we found in hamsters are consistent with what we know about depression in humans," said Tracy Bedrosian, who led the study, published in the journal Molecular Psychiatry.
Although exposure to night-time light has been linked to an increased risk of breast cancer and obesity, the relationship with mood disorders is poorly understood.
The hamsters involved in the experiment were exposed for four weeks to dim light at night - equivalent to a television screen in a darkened room - and the results compared to a control group exposed to a normal light-dark cycle.
The experimental group was then moved back onto a normal cycle for one, two or four weeks before they were tested.
The results showed they were less active and had a lower than usual interest in drinking sugar water - both symptoms are comparable to signs of depression in people.
The similarity extended to their biological make-up. The researchers found changes in the hippocampus - a part of the brain - that were consistent with people suffering depression.
The hamsters exposed to dim light at night were also shown to produce more of a protein called tumor necrosis factor (TNF), a chemical messenger that is mobilised when the body is injured or infected and causes inflammation in its efforts to repair the damage.
"Researchers have found a strong association in people between chronic inflammation and depression," said Randy Nelson, who also worked on the study. "That's why it is very significant that we found this relationship between dim light at night and increased expression of TNF."
The scientists found that blocking the effects of TNF with a drug prevented signs of depression in the hamsters, though some other indicators in the structure of the brain were unaffected.
For instance, hamsters that were exposed to dim light at night still showed a much reduced density of dendritic spines - hairlike growths on brain cells that are used to send chemical messages from one cell to another.
The overall symptoms of depression were reversible, the researchers said. Those hamsters returned to a normal light-dark cycle saw both their TNF levels and the density of their dendritic spines return to normal after about two weeks.
"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 minimizing their exposure to artificial light at night," Bedrosian said.
The discovery is the closest scientists have come so far to finding a true Earth twin
An ambitious project in Turkey's south could see a pioneering clean energy project.
Depending on local weather conditions, the eclipse was visible across a swath of the United States
Google and Facebook have been competing in innovative ways to increase internet access globally and tap into previously untouched markets.
A 14-year-old Dutch girl who sent a terror threat to American Airlines as a Twitter “joke” has been arrested by police in Rotterdam
The legal action is the first to emerge from a humiliating episode for Microsoft, which the software company has never fully explained and has accounted for only as a "technical error."
The widespread bug surfaced late on Monday, when it was disclosed that a pernicious flaw in a widely used Web encryption program known as OpenSSL opened hundreds of thousands of websites to data theft.
For some, increased connectivity has allowed them to see social network and sharing websites like Youtube and Facebook for the first time.
The suspects exploited the fact that some users had the same pin number or password for both credit cards and the loyalty card to create fake cards and charge items earlier this year
The radar is part of a safety system that ensures a failed rocket will not threatened populated areas.
The World's latest solar energy technologies with innovative products produced in Turkey will be showcased at the fair.
Kaspersky Lab uncovered evidence that a few hacking groups believed to be involved in state-sponsored cyber espionage were running such scans shortly after news of the bug first surfaced
Facebook did not specify how many ads will now appear in the right-hand column, though a sample image on the blog showed a single ad in the right-hand column
StoreDot's device charged a dead Samsung S4 smartphone battery in 26 seconds during a demonstration of the product.
Weapons like the electromagnetic rail gun could help U.S. forces retain their edge and give them an asymmetric advantage over rivals, making it too expensive to use missiles to attack U.S. warships because of the cheap way to defeat them.