As we leave the fall behind us and transition to winter, the environment that we live in goes through many changes. The days become shorter, and there’s a chance we never see the sun at all. This often negatively impacts many people and is given the term “winter blues.” Winter blues are a normal phenomenon, yet, in some cases, these environmental impacts can influence every aspect of a person’s life, drowning each activity with negative emotions. This is called seasonal affective disorder (SAD), a form of depression.
SAD is characterized as a form of depression that occurs for a period of about five months of the year periodically. Since it is a form of depression, SAD has similar symptoms, which may include daily depressive thoughts, lack of interests, weight/appetite gain or loss, sleep issues, low energy or easy agitation, hopelessness, difficulty concentrating, and suicidal thoughts. Millions of Americans suffer from SAD, especially those who live further north where daylight hours are shorter. These light deficiencies are the main cause for a seasonal affective disorder and are the reason bright light therapy has been observed as an effective treatment.
Getting about 30 minutes of white light every morning seems
to be the most effective way to combat a seasonal affective disorder.
Image Source: Malte Mueller
Bright light therapy was first proposed in 1984 (around the time SAD was recognized). Since light deficiency is a major component in SAD, exposing a patient to bright white light was the idea to try relieving their symptoms. Since 1984, many studies have been performed to optimize the technique. Undergoing about 30 minutes of white light every morning from autumn to spring appears to be the most effective, yet many variations are possible. But, why does bright light therapy work?
The circadian rhythm is the clock that regulates the physiological processes in the human body. This internal clock is far from perfect and needs to be trained from external input such as the 24 hour day/night cycle. Light exposure trains this clock. The current hypothesis for why SAD developed is called the “phase-shift hypothesis”. This hypothesis states that there is an optimal relationship between the sleep/wake cycle and our circadian rhythm. During the seasons when days are shorter, our circadian rhythm drifts behind the sleep/wake cycle causing a change in mood. The exact mechanism for why bright light therapy fixes this lagging circadian rhythm is not well known. One of the two leading ideas is that the light therapy somehow corrects this delay between the two clocks; the other is that it may increase a patient’s level of serotonin (a major component in one’s mental health). For the therapy to be effective, the patient’s eyes must be exposed to the bright light. Regardless of the exact mechanisms, bright light therapy has shown to be an effective and easy way of combating a seasonal affective disorder.
Featured Image: © Maridav / Adobe Stock
