Darkness and Mental Health

Last week a study surfaced which found a strong link between exposure to low levels of light whilst sleeping and depression. For the biohackers reading this it’s no surprise as we understand that total darkness at night is a must for optimal sleep. Even the tiniest crack in you curtains can let in sleep disrupting light from outside sources such as street lights, neighbors bad lighting habits and car headlights.

In the UK many councils, in a bid to save more money to back hand somewhere else beneficial for them, have switched to high powered energy saving white LED lights in street lamps and car head lights. This was highly apparent to me on a recent trip to the UK where the lights from car headlights on the way back from the airport were giving me the feeling of going blind in that short space of time. They were incredibly bright and had me reaching for my blue blockers immediately.

Going back to the study, it also showed that the smallest amounts of light in your room at night can also influence mood and mental wellbeing. It may seem futile to worry about a small amount of light in your rooms considering most people will have a TV in their rooms, LED alarm clock, laptop and of course their life partner – the smart phone.

The study which took place in Japan showed that just 5 lux of light was enough to trigger depression symptoms in the subjects. 5 lux is equivalent to a small amount of light from a street lamp entering ones bedroom through a crack in the curtains. To put this into perspective 1 lux is the same as what is emitted from a candle.

Some takes on the findings from light therapists were dumbfounded by the results given they use lights to treat disorders such as seasonal effective disorder (SAD) but what these medical buffoons are not understanding is the timing of light along with the colour is of upmost importance.

It’s pretty simple really, mess with your sleep and you mess with your hormones, messed up hormones equals mismatch diseases such as depression, anxiety and low mood. Light elevates cortisol, chronically high cortisol equals depression and anxiety, and it’s really that simple! Poor sleep gives you fatigue; stimulants such as caffeine give you an alert feeling through a different pathway. The effect of caffeine lessens over time so we drink more, caffeine disrupts circadian sleep wake cycles which makes you more tired, so more caffeine is needed, which leads to anxiety and depression, its that simple.


Wearing your blue blockers before bed is often not enough; you need to be in total darkness when you sleep. Therefore you need one of two things; a silk sleep mask or black out curtains.

More on the study here

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