Humans have a complicated, but vital relationship with sunlight. Like all life on our planet, we need it to survive, but too much or too little time in the sun can lead to serious problems.
To much exposure to the sun can quite quickly lead to sunburn, heat stroke, dehydration and even death in extreme cases.
It might take a little longer to happen, but too little sunlight can also have negative consequences. For example, ill-health associated with Vitamin D deficiency and the development of psychological symptoms like depression and sleep problems.
How does light deprivation affect the mind?
The connection between sunlight and human mental health is complex, but can be summed up accordingly:
- Many of our biological processes, such as sleep, follow a 24-hour cycle. Exposure to sunlight helps keep your internal body clock on schedule.
This day-long cycle is referred to as the circadian rhythm. The key point to consider for now is that the bodily processes that follow the circadian rhythm can be disrupted by a lack of sunlight.
The result of this disruption can be the development and/or worsening of psychological problems.
What are the psychological effects of light deprivation?
While a number of mental health symptoms can be associated with a lack of sunlight (insomnia, delayed sleep, etc.), the most interesting result may be something called Seasonal Affective Disorder (SAD).
SAD is no longer considered a mental illness on its own (as it had been until the release of the DSM-V psychology manual). Instead, it’s now categorized as a specifier.
This means that it only occurs as an addition to an underlying ailment, like major depression or bipolar disorder. For example, a person who experiences low moods and fatigue during the low-light winter months may be diagnosed as having major depressive disorder with SAD.
The exact symptoms experienced by SAD sufferers can vary widely depending on the underlying condition and individual characteristics. For example:
- People with bipolar disorder may start cycling through moods at an increased rate, even if they remain relatively stable during non-winter months.
- People with depression could experience more extreme and frequent drops in mood.
In most cases, symptoms related to the root disorder that are present year-round will be intensified during the winter months, while new symptoms (usually in the range of those typical of the underlying condition) may also appear.
The symptoms associated with SAD will eventually weaken as sunlight returns in the Spring. And in some cases they may even disappear during the rest of the year.
How can light deprivation be treated?
There are multiple approaches to treating the symptoms related to light deprivation, such as those experienced by people with SAD.
Medication (like antidepressants) and/or Cognitive Behavioral Therapies (CBT) are often used. The exact choice will depend on the severity of symptoms and if they are seasonal or all-year round.
The ideal approach to treating light deprivation is of course to obtain more sunlight though. However, this isn’t always possible due to geographic location or lifestyle demands.
Luckily, there’s another solution available in the form of light therapy that people can use in their own time and in their own home.
What is light therapy?
Light therapy refers to the use of a light box (a special lamp) designed to consistently emit extremely bright light.
These devices are often suggested to people with SAD for use during low-light months. They can also be used during the year if people suffer from light deprivation because of location, lifestyle or work.
Daily sessions lasting 20-30 minutes are a common starting schedule. Some people might require a different amount of exposure based on their unique conditions and responses to therapy though.
In the past, light therapy sessions would normally take place under the supervision of a medical professional. Nowadays, people can buy light therapy devices through a variety of retailers to use while at home or work. Still, discussing the product with a medical professional prior to use is advisable.
Research showing the effectiveness of light therapy
The manufacturers of many light therapy devices report that they conducted scientific studies which confirm the effectiveness of their product.
Unfortunately though, it’s often difficult (or impossible) to obtain the official reports. So it’s not a good idea to rely on the claims of manufacturers alone.
Luckily, there’s plenty of independent evidence suggesting light therapy is an effective treatment for the psychological symptoms related to sunlight deprivation:
- A 2015 study of 177 adults with major depressive disorder and SAD found that light therapy was equally effective to CBT in reducing depression severity after six weeks of treatment.
- Patients with SAD reported a modest but significant reduction in depression symptoms after receiving just a single hour of light therapy in a 2012 experiment.
- Light therapy can also be used in combination with other treatment methods. An investigation conducted in 2015 with 50 inpatient participants found that light therapy plus an antidepressant (venlafaxine) reversed the symptoms of major depressive disorder more rapidly and effectively than venlafaxine alone.
- A 2016 meta-analysis of 9 previous studies (with 489 total participants) determined that light therapy was associated with significantly decreased symptom severity in people suffering from bipolar disorder with SAD.
There are also studies that help clarify some of the treatment’s finer characteristics and underlying mechanisms of action:
- Light therapy is known to work best when sessions occur early in the morning after first waking. This is why many light therapy boxes are marketed as “wake-up lights”. A 2015 investigation showed that the effect may be a result of changes to the way parts of the brain react to serotonin (a chemical produced within the brain that’s related to mood regulation).
- There’s little agreement among professionals about the exact type of light that’s most beneficial. When describing light by its color (which is directly related to its frequency), it was once a common belief that blue light is essential to the process. However, a new experiment failed to detect a difference between the improvements experienced by people treated with only blue light or blue-free light. Instead, both types of light proved to be equally effective.
Can wake-up lights help with the winter blues?
In addition to light therapy devices, there are many different kinds of wake-up lights available. Most of these don’t have the same intensity of light as medical-grade light therapy devices, but are still designed to help combat the winter blues.
In the winter months, or darker regions of the planet, many people find it hard to wake up in the morning and face the day with a smile.
It can be especially difficult if the sun still hasn’t risen when you wake up to go to work, and you’re woken up by a sudden and jarring alarm clock tone.
The idea of wake-up lights is to wake you up slowly and calmly by simulating the sunrise right in your bedroom. They can be programmed to start 15-60 minutes before the time you want to wake up, slowly filling the room with light.
The makers of wake-up lights say their research has shown that people wake up easier, feel more positive and are more productive during the day. Again, it’s not easy to confirm these results, but anecdotal reports from people who use them do suggest they work well.
So if you find it difficult to wake up in the depths of the winter, and struggle to get out of bed, you might find a wake-up light is a good first step before trying more serious light therapy devices or other medical treatment.
Are you affected by a lack of sunlight because of where you live, or other factors such as work or lifestyle? How does it impact on your mood and daily life?
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