Have you ever noted that you just sleep more within the winter months? Or eat more carbs or have low energy? If you do, you then could be certainly one of the around 6% of the higher latitude populations with seasonal affective disorder (SAD).
If you’ve searched the web for recommendations on how you can fight the winter blues you’ve probably been advised to purchase a therapy lamp. So you could be wondering what research says about whether or not they are effective and the way they work.
Before we examine the evidence for light therapy it’s vital to know why mood could be affected by sunlight. Vitamin D is produced when your skin is exposed to sunlight and a few scientists imagine there may be a link between depression and low vitamin D levels.
Studies have found about 10% of the population of the far northfor instance in Alaska and Finland, experience SAD. Interestingly, Icelanders, who also live in these very northern latitudes, don’t appear to suffer a lot from SAD. This could be due to their fish-packed eating regimenwhich is wealthy in vitamin D.
Light also stimulates your visual system, regulating activity within the so-called circadian pacemaker. This is the suprachiasmatic nucleus (SCN), a small region of the brain. The SCN gets direct input from the retina and can also be filled with melatonin receptors. Melatonin supplements are actually being touted as a treatment for depression. So there are multiple the reason why light could be vital for mood.
SAD was first described around 1980 within the US when a person, who experienced the symptoms outlined above, invented a light-weight box to treat himself.
There have been many studies since examining light therapy in SAD with mixed and contradicting results. However, data from all these studies may be combined and examined using meta-analyses to offer a more accurate overall picture. A meta-analysis merges the findings of several independent studies. There have been several meta-analyses of this topic and most show that light therapy has a positive effect, not only on SAD, but additionally on major depression.
Does light intensity matter
Light intensity is measured in lux. A 1999 meta-analysis of 39 scientific papers found that strong light intensity (6,000-10,000 lux) had a greater effect than medium light intensity (1,700-3,500 lux). Medium light intensity had a greater effect than dim lighting (lower than 600 lux) on depressive symptoms in individuals with SAD. A 2019 meta-analysis of 19 studies also found that brighter light (greater than than 1,000 lux) is required to treat SAD.
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You could be wondering whether light color matters.
A 1997 meta-analysis checked out 40 scientific papers examining different colors of sunshine. It revealed that light of short to medium wavelengths (blue, green and yellow) were effective but that red or UV wavelengths didn’t appear to treat SAD. This study also reviewed the timing of the phototherapy. The data, although not significant (which suggests more studies are needed), suggested that phototherapy in each the morning and the evening was simpler than morning or evening alone.
Does phototherapy work in non-seasonal depression?
A 2005 meta-analysis of 23 studies found phototherapy worked for individuals with SAD and for individuals with non-seasonal depression. This paper reviewed six studies of combined treatment for non-seasonal depression. It found that phototherapy, although effective alone, didn’t produce a greater effect on depression symptoms when given along with antidepressant medication.
However, more moderen studies agree that the mix treatment is simpler. A 2016 meta-analysis of ten studies did find phototherapy augmented drug treatment of depression. A 2019 meta-analysis of seven studies also found it increased the facility of antidepressants.
So for those who suffer from non-seasonal depression, then phototherapy may go as a primary line treatment and can probably boost the consequences of any antidepressant drug that you could be taking.
There can also be a condition called sub-syndromal SAD (SSAD or sub-SAD) affecting about 10-15% of upper latitude populations, where symptoms are milder or less frequent than SAD. Sub-SAD may also be treated with light therapy.
Vitamin D is essential for physical health in addition to mental health because it regulates calcium and phosphate levels, is critical for good bone density and for muscle and teeth health. It’s also essential for a healthy immune system.
There are other studies that have a look at lighting within the workplace and the effect on employees, for instance certain forms of light might improve alertness, while other lighting might increase headaches.
If you suffer from SAD, select the next intensity light for a faster effect, use the sunshine for longer, for instance, each morning and evening sessions. Avoid UV light which is ineffective for SAD and may result in sunburn or skin cancer. And don’t forget to eat some fish to spice up your vitamin D levels too.