What Color Is Your Night Light? It May Affect Your Mood

Hamsters exposed to red light at night had significantly less evidence of depressive-like symptoms and changes in the brain linked to depression, compared to those that experienced blue or white light. (Credit: © Stephen Coburn / Fotolia)

Aug. 6, 2013 — When it comes to some of the health hazards of light at night, a new study suggests that the color of the light can make a big difference.

In a study involving hamsters, researchers found that blue light had the worst effects on mood-related measures, followed closely by white light.

But hamsters exposed to red light at night had significantly less evidence of depressive-like symptoms and changes in the brain linked to depression, compared to those that experienced blue or white light.

The only hamsters that fared better than those exposed to red light were those that had total darkness at night.

The findings may have important implications for humans, particularly those whose work on night shifts makes them susceptible to mood disorders, said Randy Nelson, co-author of the study and professor of neuroscience and psychology at The Ohio State University.

“Our findings suggest that if we could use red light when appropriate for night-shift workers, it may not have some of the negative effects on their health that white light does,” Nelson said.

The study appears in the Aug. 7, 2013, issue of The Journal of Neuroscience.

The research examined the role of specialized photosensitive cells in the retina — called ipRGCs — that don’t have a major role in vision, but detect light and send messages to a part of the brain that helps regulate the body’s circadian clock. This is the body’s master clock that helps determine when people feel sleepy and awake.

Other research suggests these light-sensitive cells also send messages to parts of the brain that play a role in mood and emotion.

“Light at night may result in parts of the brain regulating mood receiving signals during times of the day when they shouldn’t,” said co-author Tracy Bedrosian, a former graduate student at Ohio State who is now a postdoctoral researcher at the Salk Institute. “This may be why light at night seems to be linked to depression in some people.”

What people experience as different colors of light are actually lights of different wavelengths. The ipRGCs don’t appear to react to light of different wavelengths in the same way.

“These cells are most sensitive to blue wavelengths and least sensitive to red wavelengths,” Nelson said. “We wanted to see how exposure to these different color wavelengths affected the hamsters.”

In one experiment, the researchers exposed adult female Siberian hamsters to four weeks each of nighttime conditions with no light, dim red light, dim white light (similar to that found in normal light bulbs) or dim blue light.

They then did several tests with the hamsters that are used to check for depressive-like symptoms. For example, if the hamsters drink less-than-normal amounts of sugar water — a treat they normally enjoy — that is seen as evidence of a mood problem.

Results showed that hamsters that were kept in the dark at night drank the most sugar water, followed closely by those exposed to red light. Those that lived with dim white or blue light at night drank significantly less of the sugar water than the others.

After the testing, the researchers then examined the hippocampus regions of the brains of the hamsters.

Hamsters that spent the night in dim blue or white light had a significantly reduced density of dendritic spines compared to those that lived in total darkness or that were exposed to only red light. Dendritic spines are hairlike growths on brain cells that are used to send chemical messages from one cell to another.

A lowered density of these dendritic spines has been linked to depression, Nelson said.

“The behavior tests and changes in brain structure in hamsters both suggest that the color of lights may play a key role in mood,” he said.

“In nearly every measure we had, hamsters exposed to blue light were the worst off, followed by those exposed to white light,” he said. “While total darkness was best, red light was not nearly as bad as the other wavelengths we studied.”

Nelson and Bedrosian said they believe these results may be applicable to humans.

In addition to shift workers, others may benefit from limiting their light at night from computers, televisions and other electronic devices, they said. And, if light is needed, the color may matter.

“If you need a night light in the bathroom or bedroom, it may be better to have one that gives off red light rather than white light,” Bedrosian said.

Other co-authors of the study were Celynn Vaughn, Anabel Galan, Ghassan Daye and Zachary Weil, all of Ohio State.

The work was supported in part by a fellowship to Bedrosian from the U.S. Department of Defense.

http://www.sciencedaily.com/releases/2013/08/130806203150.htm

 

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Infections increase risk of mood disorders

Contact: Michael Eriksen Benrós benros@ncrr.dk 45-26-25-52-39 Aarhus University

New research shows that every third person who is diagnosed for the first time with a mood disorder has been admitted to hospital with an infection prior to the diagnosis

New research shows that every third person who is diagnosed for the first time with a mood disorder has been admitted to hospital with an infection prior to the diagnosis. The study is the largest of its kind to date to show a clear correlation between infection levels and the risk of developing mood disorders.

Anyone can suffer from an infection, for example in their stomach, urinary tract or skin. It would now appear that their distress does not necessarily end once the infection has been treated. A new PhD project shows that many people subsequently suffer from a mood disorder:

“Our study shows that the risk of developing a mood disorder increases by 62% for patients who have been admitted to hospital with an infection.  In other words, it looks as though the immune system is somehow involved in the development of mood disorders,” says Michael Eriksen Benrós, MD and PhD from Aarhus University and Psychiatric Centre Copenhagen.

He is behind the study together with researchers from Aarhus University and the University of Copenhagen as well as The Johns Hopkins University in the USA.

Three million Danes included

The study is a register study, which has involved following more than 3 million Danes. Between 1977 and 2010, more than 91,000 of these people had hospital contact in connection with a mood disorder.  It transpired that 32% of the patients had previously been admitted with an infectious disease, while 5% had been admitted with an autoimmune disease.

According to Michael Eriksen Benrós, the increased risk of mood disorders can be explained by the fact that infections affect the brain:

“Normally, the brain is protected by the so-called blood-brain barrier (BBB), but in the case of infections and inflammation, new research has shown that the brain can be affected on account of a more permeable BBB.”

“We can see that the brain is affected, whichever type of infection or autoimmune disease it is. Therefore, it is naturally important that more research is conducted into the mechanisms which lie behind the connection between the immune system and mood disorders,” says Michael Eriksen Benrós.   He hopes that knowing more about this connection will help to prevent mood disorders and improve future treatment.

Facts

  • 3.56 million Danes born between 1945 and 1996 were followed via the Danish patient registers.
  • Of these, 91,637 had hospital contact in connection with a mood disorder.
  • The study has been financed by the Stanley Medical Foundation and the National Institute of Mental Health in the USA.
  • The findings have just been published in the prestigious international journal JAMA Psychiatry.

 

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Further information

Michael Eriksen Benrós, MD and PhD Aarhus University and the University of Copenhagen Tel.: +45 2625 5239 benros@ncrr.dk

Over-activity of the serotonin system may relate to mood disorders such as depression and anxiety

Contact: Mary Kohut Press@plos.org 415-568-3457 Public Library of Science

Why serotonin can cause depression and anxiety

Mood disorders could be caused by a loss of our inherent, reflexive avoidance of aversive events, according to a study published in PLoS Computational Biology.  Researchers from UCL in London and Columbia University in New York used computational modeling techniques to integrate what appeared to be blatant contradictions between serotonin’s roles in different states of health.

Serotonin appears to be one of the major players in mood and a variety of other disorders. But exactly how remains an open question. Imagine walking past a dark alleyway in a dangerous part of some city; although it might be a shortcut, most people wouldn’t consider taking it. In healthy subjects, serotonin appears important for this automatic avoidance.

It has long been suggested that over-activity of the serotonin system may relate to mood disorders such as depression and anxiety, as these seem characterized by too much withdrawal and avoidance. However, the new modeling study simply suggests that we think about what happens when these reflexes fail—suddenly you have to think hard to avoid things that used to be avoided reflexively You might for example consider walking down the dangerous alley, be robbed and thus be reminded and taught by additional experience that dark alleys are to be avoided.

In this study Prof. Peter Dayan and Dr. Quentin Huys built a reinforcement learning model of reflexive choices. Agents take actions and as a result of these move through a set of states, some of which are rewarded or punished. As agents progress through this space, they learn the value of each state—how much punishment or reward is to be expected from this state onwards.

It turns out that adding to the agent’s behavioural repertoire a simple reflex, which guides the agent away from an action with potential for poor consequences, does two things: it increases the rewards reaped overall, but, because bad states are now not explored any more, it also prevents them from learning exactly how bad these bad states are. When serotonin drops, say in depression or anxiety, agents have no more recourse to the reflexive avoidance and have to rely on what they learned. Because they have not learned how bad the bad states are, they start exploring states that don’t look too bad to them, but in reality are much worse. Serotonin enhancing drugs, such as Prozac, are then suggested to reinstate the reflexive avoidance, and thus to redress the balance.

This study gives insight into some puzzling findings—for example, it argues that the association of depression with aggression may have to do with a lack of reflexive avoidance of it. In addition, stress not only causes depression, but people with depression experience more stressors. Again, this may be related to a dysfunctional reflexive avoidance system. The study, however, vastly oversimplifies a number of issues, such as the flexibility of reflexive actions, and the effect of non-reflexive action choice. These provide interesting avenues for further research, and may in fact give some insight into the co-morbidity of different mood disorders.

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PLEASE ADD THIS LINK TO THE PUBLISHED ARTICLE IN ONLINE VERSIONS OF YOUR REPORT: http://compbiol.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pcbi.0040004

CITATION: Dayan P, Huys QJM (2008) Serotonin, inhibition, and negative mood. PLoS Comput Biol 4(1): e4. doi:10.1371/journal.pcbi.0040004

CONTACT:

Dr. Quentin Huys Center for Theoretical Neuroscience Columbia University qhuys@gatsby.ucl.ac.uk +1-917-251-1641

****For immediate release: an embargo does not apply to this article****

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Reposted from 2008 at request

Live Vaccination against ( German Measles ) Rubella caused Signifigant Depression up to 10 weeks – Vaccines/ Bacteria Can Alter Mood and Behavior


Mood Disorders

April 30, 2007

Norman Sussman, MD, DFAPA Editor, Primary Psychiatry and Psychiatry Weekly, Professor of Psychiatry, New York University School of Medicine

There is growing interest in a suspected cause of some cases of depression: infection and inflammatory response. New research findings that add to our understanding of the interrelationship of immunology and depression, and the reasons that some currently used antidepressants work, may fundamentally change the way that mood disorders and drug therapies are conceptualized.

There are several unambiguous examples of psychiatric illness being the result of an inflammatory or immune reaction.  Considerable evidence already exists about the Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections (PANDAS), a disorder in which Streptoccal infection triggers an autoimmune response. The antibodies that form against the invading bacteria mistakenly recognize and “attack” certain parts of the brain, causing psychiatric symptoms.

Another notable example of immune-mediated depression is the response of some patients to treatment with Interferon α, who become profoundly depressed and suicidal. Interestingly, onset of depressive symptoms has been shown to be prevented by treatment with antidepressants that work on the serotonin system.

The involvement of immune activation and depressive-like “sickness behavior” symptoms has been suspected for many years. Evidence specifically suggests that patients with major depression exhibit changes in cytokine activity and inflammation. Immune-mediated psychological and neuroendocrine changes were observed following vaccination with live attenuated rubella virus. A subgroup of vulnerable subjects showed a significant virus-induced increase in depressed mood up to 10 weeks following their vaccination. In a related animal study, the investigators also showed that immune activation with a variety of immune challenges induced a “depressive-like syndrome in rodents: anhedonia, anorexia, body weight loess, and reduced exploratory, and social behavior.” Chronic treatment with TCAs or SSRIs attenuated many of the behavioral effects.

A team of English investigators have, for the first time, shown a possible link between administration of a vaccine, peripheral immune activation, psychological and behavioral changes, and the brain serotonin system. The researchers used antigens derived from the bacterium Mycobacterium vaccae, a generally benign and ubiquitous agent found in dirt. After vaccination, they found that the subsequent immune activation was temporally associated with increases in serotonin metabolism within the ventromedial prefrontal cortex. Treatment with the vaccine seemed to alter behavior in mice similarly as is typically seen with antidepressants. This research was initiated following observations that human cancer patients being treated with the bacteria Mycobacterium vaccae unexpectedly reported increases in their quality of life.

The identification of serotonin neurons in the dorsal raphe nucleus that are uniquely responsive to peripheral immune activation raises the possibility that one day there will be a vaccine designed to modulate the immune response which in turn will the prevent the onset or attenuate the symptoms of major depression and other psychiatric disorders

Repsoted at Request