(This story has been republished on World Sleep Day, which falls on 18 March 2022.)
Blue light, an obsequious presence in urban lifestyle, might have a bigger role to play in our lives than we realise at first glance. From its effects on sleep to mental health, the speculations and research around it are more rife and endless, leading us to bring in an expert to comment on it.
Before looking at blue light specifically, which is in galore in our screens, be it smartphones, televisions, or computers, as well as indoor LED lighting, it should be pointed out that light of any kind affects your circadian rhythm which has a direct control on your sleep, and therefore, in the process, on mental health and mood disorders.
Light, Sleep and Mental Health
Light of any kind influences the secretion of melatonin in your body, the hormone that controls your sleep-wake cycle, but according to Harvard Health Publishing, blue light does it more significantly.
The report reads:
“Scientists think nighttime exposure to blue light throws off your circadian rhythm, or sleep/wake cycle. This could lead to symptoms of depression. That’s because your circadian rhythm plays a role in several brain and behavioural processes, like neurotransmission and hormone secretion.”
Dr Bindu Menon, Professor and Head, Department of Psychiatry, Amrita Hospitals, Kochi, Kerala comments on the role of light in our mental health,
“All our body processes are cyclic in nature and dependant on the circadian rhythm or body clock. We are adapted to the solar cycle of day and night. This is done through many hormones of which the most well known are orexin and melatonin. When exposure to light is mistimed or nearly constant, biological and behavioural rhythms can become desynchronised, leading to negative consequences for health.”
Dr Menon further points out that today over 80 percent of the population, especially in urban areas, experience nightly light pollution. With technological advances, we encounter even more sources of light at night of which blue light is an integral part.
According to the National Sleep Foundation, USA, 36 percent of parents and 34 percent of children leave an electronic device such as a television or computer switched on in their rooms while sleeping. In addition, 87 percent of women watch television in the hour before bedtime
Pervasive exposure to nighttime lighting has blurred the boundaries of day and night, making it more difficult to synchronize biological processes, says Dr Menon. Many systems under circadian control, including sleep–wake behaviour, hormone secretion, cellular function and gene expression are altered because of this and are now believed to be associated with increasing incidence of certain cancers, metabolic dysfunction and mood disorders.
Blue Light or Not, Listen to Your Sleep Cycle
The circadian disruption, underlines Dr Menon, alters the function of brain regions involved in emotion and mood regulation through direct neural input from the biological clock or indirect effects, including altered neuroplasticity (the way in which the neurons repair themselves), neurotransmission and gene expression.
Even though studies and research are ongoing on specifically the effects of blue light, we have sufficient evidence to conclude that it indeed has a significant role to play in our mental health.
There is no real scientific evidence to say that the hues or colour of light have any psychological effects on mood, though blue light has been shown to increase subjective alertness and performance on attention-based tasks in a few studies. The bottom line is - light is not bad, but the timing of exposure to it, which goes against our natural biological rhythm is what causes problems.Dr Bindu Menon