We need light to feel energized and happy.  Our mood and energy depend upon getting sufficient bright light during the day to signal ‘awake and alert’.  Without this signal, our bodies can’t clearly distinguish between night and day, and don’t provide the energy and hormones we need to feel our best.  Studies suggest that 1 in 5 of us experience a mild version of the winter blues, while 1 in 20 suffer from Seasonal Affective Disorder (SAD).   In my own experience, the winter blues come and go = I feel down after a few days of gloomy weather, or after being stuck inside for too long.   My mood lifts with sunny weather, and with time spent outdoors.  From October through March our nights are longer than our days, and most of us don’t go outside to bask in the winter sun.  Living in northern climates or with poor weather makes getting enough light even harder.  Long hours spent indoors exacerbates the winter blues as most indoor environments aren’t lit brightly enough to stimulate our bio-rhythms.  To varying degrees we’re all sensitive to light, we’ve evolved that way – the winter months make it especially difficult to get the natural light we need to feel our best.


As described in in the scientific literature and summarized on our science page (and in other blog posts), we depend upon a strong daily light/dark cycle to regulate the circadian rhythms which underpin our health and wellness.  Insufficient light during the day has been linked to poor sleep, depression, weight gain and chronic disease.  The winter blues can range from mild to serious, please reach out to your physician if you have the feeling that things aren’t going to get better, your work or personal relationships are impacted, or you have suicidal thoughts.


Days grow shorter, and the intensity of the sun drops 5x from summer to winter in northern latitudes (Figure for London in the UK – excerpted from this article).

Exposure to bright light triggers your body’s ‘awake and alert’ response, and clinical studies suggest >10,000 lux is needed (lux is a measure of light intensity).  Daylight can range from >100,000 lux (on sunny summer days) to 20,000 lux in the shade, to less than 2000 lux on an overcast day (wikipedia).   Most indoor lighting delivers less than 500 lux so spending time under artificial lights won’t help.    The availability of natural light is impacted by how far north you live, with your latitude dictating both how many hours of daylight you receive in the winter and the angle of the sun in the sky (lower angles = more atmospheric filtering and less bright blue light).   This makes getting enough light in the winter especially difficult for those who live in northern climates.  It’s no accident that we consider dark grey skies to be ‘gloomy’ weather.