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Good evening all, and happy Easter.
It’s a sunny bank holiday weekend and I've been thinking about the effects of sunlight.
Rather unconventionally for an undergraduate economics student, I wrote my dissertation on Seasonal Affective Disorder (winter depression) and its impact on labour productivity. I am fascinated by the effects of the weather on mood and productivity, given I feel like a completely different person in summer to the one who struggles through winter.
SAD is linked to daylight duration. People with SAD have difficulty regulating the neurotransmitter serotonin, which regulates mood. As sunlight diminishes in winter, serotonin levels fall (as well as vitamin D production). Additionally, these people simultaneously overproduce melatonin, the hormone which responds to darkness by causing sleepiness. The combination of decreased serotonin and increased melatonin impacts circadian rhythms (our internal 24-hour "biological clock" regulating various physiological processes, including sleep and wakefulness). Spring and summer then bring significant well-being improvements.
Now, this is a rather extreme case. However, the amount, timing and type of light exposure we get daily significantly impacts our health and well-being and, therefore, our ability to perform at our best.
The science of light exposure
Recently I’ve been listening to many podcasts conducted with experts on science-backed ways to improve our health and well-being (such as Huberman Lab, hosted by Andrew Huberman, a neuroscientist and professor at Stanford University). Here are the most common suggestions.
Experts advocate getting exposure to bright light first thing in the morning to regulate our circadian rhythm, which can improve sleep quality and increase energy levels throughout the day. The mechanisms are through serotonin and melatonin explained above, with possible effects on prefrontal cortex activity in the brain improving cognitive performance. The light should be unfiltered, i.e. we should be getting it outdoors and not through a window, so a walk first thing in the morning is recommended. Interior lights should be bright and ideally positioned high and above our heads.
In the evening we should dim lights and position them low to signal to our bodies that it is time to wind down and prepare for sleep. This can improve the quality and duration of our sleep. In addition, we should limit exposure to blue light from electronic devices in the evening. This type of light can disrupt our sleep-wake cycle and suppress the production of melatonin, a hormone essential for sleep.
I use ‘night mode’ on all devices from the early evening to limit the blue light from them, and then stop all screen usage an hour before bed. Blue-light-blocking glasses are another popular way to help mitigate these effects.
Implementation idea
Consider whether you are utilising light in the right way to boost your energy levels and the quality of sleep.
As I discussed earlier this year (link), sleep is crucial for physical and mental health and well-being, especially for peak performance. You can find my healthy habits for sleep in that post. Sleep well.
Best, Alex Joshi.
On my bedside table:
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