Using mice as model, University of Virginia researchers discover light plays a role in reducing fear and anxiety.
This finding and application may augment the treatment of a variety of mental disorders including depression, anxiety, panic disorders, phobias and post-traumatic stress disorder.
The research builds on earlier findings by biologists and psychologists showing that light affects mood with the new study demonstrating light can modulate fear.
As mice are nocturnal animals, the researchers discovered intense light enhances fear or anxiety in mice, in much the same way that darkness can intensify fear or anxiety in diurnal humans.
The finding is published in the journal Proceedings of the National Academy of Sciences.
“We looked at the effect of light on learned fear, because light is a pervasive feature of the environment that has profound effects on behavior and physiology,” said Brian Wiltgen.
“Light plays an important role in modulating heart rate, circadian rhythms, sleep/wake cycles, digestion, hormones, mood and other processes of the body. In our study we wanted to see how it affects learned fear.”
Fear is a natural mechanism for survival and is often an instinct. For example, fears or reactions to loud noise, sudden movements and heights are innate.
In addition, humans and other mammals can learn from their experiences which may include dangerous or bad situations. This “learned fear” can protect us from dangers.
Unfortunately, this fear can become abnormally accentuated, sometimes leading to debilitating phobias. About 40 million people in the United States suffer from dysregulated fear and heightened states of anxiety.
“Studies show that light influences learning, memory and anxiety,” Wiltgen said. “We have now shown that light also can modulate conditioned fear responses.”
“In this work we describe the modulation of learned fear by ambient light,” said Ignacio Provencio, an expert on light and photoreception.
“The dysregulation of fear is an important component of many disorders, including generalized anxiety disorder, panic disorder, specific phobias and post-traumatic stress disorder.
Understanding how light regulates learned fear may inform therapies aimed at treating some of these fear-based disorders.”
“The implications of this in humans is this: that being diurnal, the absence of light can be a source of fear,” Wiltgen said.
“But increased light can be used to reduce fear and anxiety and to treat depression.
“If we can come to understand the cellular mechanisms that affect this, then eventually abnormal anxiety and fear might be treated with improved pharmaceuticals to mimic or augment light therapy.”
Source: University of Virginia