Research suggests that women with perinatal depression appear to have altered circadian rhythms, and using light to reset the body clock seems to improve their symptoms.
Our bodies run on internal clocks that are regulated by a suite of genes. In concert with light, they wake us up in the morning and leave us sleepy by night-time.
People with severe depression tend to have disrupted circadian rhythms, experiencing daytime sleepiness and night-time insomnia.
Research has found higher activity in some circadian genes in people with the condition.
Perinatal depression – which occurs during and after pregnancy – seems to be similar.
Women tend to get less sleep when they are pregnant, particularly if they have perinatal depression.
To find out if circadian genes might play a role, Massimiliano and colleagues (2019) analysed seven genes in 44 women in the third trimester of pregnancy. Thirty of the women were diagnosed with perinatal depression.
By looking at whether epigenetic tags, called methyl groups, were attached to the genes, the researchers could tell how active these genes were.
They found that three circadian genes were more active and one was less active in the women who had been diagnosed with depression. They also found that the more methyl groups there were, the more severe a woman’s symptoms were likely to be.
This suggests that the greater the difference in circadian gene activity, the more likely a woman is to experience symptoms of depression, say the researchers.
Other (unpublished) research by Katherine Sharkey, Brown University in Rhode Island, has found that using a light box to mimic natural daylight improves the symptoms of perinatal depression. In this small trial of 44 women with the condition, sharkey found that those given a light box and sleep routine alongside routine treatment saw their symptoms improve. Although all the women got better, the women given a circadian intervention did better than those without.
The evidence is not yet strong enough to recommend the treatment more widely, but there is evidence that a good sleep routine and outdoor exposure to sunlight is beneficial for mental health. For example, in a typical office space, the light level is 300 to 400 lux, but on a bright, sunny day, outside can be 50,000 lux.
References
Buoli, M., Grassi, S., Iodice, S., Carnevali, G.S., Esposito, C.M., Tarantini, L., Barkin, J.L. & Bollati, V. (2019) The Role of Clock Genes in Perinatal Depression: THe Light in the Darkness. Acta Psychiatrica Scandinavica. 140(4), pp.382-384. https://doi.org/10.1111/acps.13084.
Hamezlou, J. (2019) Light Therapy May Help Relieve Symptoms of Perinatal Depression. New Scientist. 21 September 2019, pp.15.
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