The loss of daylight hours during winter is a common cause of seasonal affective disorder (SAD), a type of depression that hits seasonally and lifts as spring and summer rolls back around.
The fact that SAD occurs when the days begin to darken and sunlight is at a minimum is not a coincidence. Your health and mood are intricately tied to exposure to sunlight. For example, your serotonin levels (the hormone typically associated with elevating your mood) rise when you're exposed to bright light.
Your melatonin level also rises and falls — inversely — with light and darkness. When it's dark, your melatonin levels increase, which is why you may feel tired when the sun starts to set, and in the heart of winter, this may be at as early as 3 p.m. if you live far from the equator. Light and darkness also control your biological clock, or circadian rhythm, which impacts hormones that regulate your appetite and metabolism.
Aside from light therapy and vitamin D, other drug-free treatment options include optimizing your omega-3 level, exercise and normalising your circadian rhythm.
The Role of Vitamin D
Vitamin D appears to play a role in the activity of serotonin, a mood-balancing hormone, and melatonin, a hormone that responds to light and dark.
People with SAD tend to have lower serotonin and higher melatonin levels, which can account for the fatigue, tiredness and depressed mood typically associated with this condition.
Vitamin D deficiency is very common, and should be a top consideration when you’re looking for a solution to flagging mood and energy — especially if it occurs during fall and winter months.
Ideally, you’ll want to get your vitamin D level tested twice a year, in summer and winter, when your levels are highest and lowest. This will help you fine-tune your dosage over time. While regular sun exposure is the best way to optimise your vitamin D level, this isn’t possible in many areas during the winter, thus necessitating the use of oral supplements instead.
Another study stated that people with lower blood levels of omega-3s were found to be more likely to have symptoms of depression and a more negative outlook while those with higher blood levels demonstrated the opposite emotional states.
A more recent review, published in 2015, pointed out that “Cell signalling and structure of the cell membrane are changed by omega-3-fatty acids, which demonstrates that an omega-3-fatty acid can act as an antidepressant.”
Importantly, this paper also points to research showing that the ratio of omega-3 to omega-6 is an important factor that can influence your depression risk. People with severe symptoms of depression have been found to have low concentrations of omega-3 in conjunction with considerably higher concentrations of omega-6.
The key, to normalising this ratio is to increase your omega-3 intake while simultaneously lowering your omega-6 consumption. This means you’ll need to avoid processed and fried foods, as they’re typically loaded with omega-6-rich vegetable oils.
Light therapy, using full-spectrum non fluorescent lighting that has blue light to artificially mimic sunlight, is among the most effective treatment options for SAD. You want to avoid fluorescent as they emit large amounts of dirty electricity. Ideally, have the light exposure in the morning, well after sunrise.
Light boxes can be purchased that emit full spectrum light similar in composition to sunlight. Symptoms of SAD and S-SAD may be relieved by sitting in front of a light box first thing in the morning, from the early fall until spring …
Typically, light boxes filter out ultraviolet rays and require 20–60 minutes of exposure to 10,000 lux of cool-white… light daily during fall and winter.
This is about 20 times as great as ordinary indoor lighting … Light therapy should not be used in conjunction with photosensitizing medications such as lithium, melatonin, phenothiazine antipsychotics, and certain antibiotics.”
Light therapy can take up to four weeks before you notice an improvement.
Blue Light During Daytime Hours May Improve Your Mood
In addition to the bright white light used in light therapy, blue light has also been shown to be useful. According to a 2010 study, blue light appears to play a key role in your brain's ability to process emotions, and its results suggest that spending more time in blue-enriched light could help prevent SAD.
Blue light is prevalent in outdoor light, so your body absorbs the most during the summer and much less in the winter. Because of this, the researchers suggested that adding blue light to indoor lighting, as opposed to the standard yellow lights typically used, may help boost mood and productivity year-round, and especially during the winter.
Keep in mind, however, that blue light after sunset or before sunrise should be avoided, as it can disrupt your circadian rhythm. In fact, one of the reasons for insomnia and poor sleep is related to excessive exposure to blue light-emitting technologies such as TV and computer screens, especially in the evening.
The blue light depresses melatonin production, thereby preventing you from feeling sleepy. So, you only want to expose yourself to blue light in the morning, and possibly afternoon, but not in the evening.