Today is the September equinox, where the sun is directly over the equator, meaning the length of day and night is equal; 12 hours each – and the seasons on either side of the world are the exact opposite.
In Australia and the Southern hemisphere it is the Spring equinox – and in the Northern hemisphere today represents the Autumn (or fall) equinox.
This seems like a timely reminder about the importance of our natural our circadian rhythms and the seasons. Time and seasonality are so important for so many health reasons, yet in the modern world it is all too easy to live a 24 hour life and barely notice the season.
By being aware of the changing length of day and intensity of the sun our bodies know what season it is. When our ancestors lived they would have experienced a far greater availability of food in the summer months. Fruit and vegetables would have only been in season for relatively short periods of time, so they would have been likely to consume as much as they could, when they could. This would have been converted to sugar and stored as fat, for sustenance during the harsher winter months. Today there is barely a week in the year, when almost all types of fruit and vegetables are not available. It makes sense that eating as though it's summer all year round might not be the best idea biologically, don't you think?
In terms of Vitamin D, the sunshine vitamin, our ancestors would have been outside most of the time. This would have given them far better levels of Vitamin D than we have today, thanks to our indoor, sun-fearing lifestyles.
Day and Night
Another big problem with our modern lifestyles, is our bodies not getting the correct signals of day and night. Our ancestors would have had no artificial exposure to the blue light we are now inundated with. Without blue light melatonin, the sleep hormone, is produced when the sun goes down. This triggers sleep. When the sun comes up, melatonin production halts rendering us alert and awake. With artificial lighting, TV and computers in the evening giving out as much blue light as sunlight, it is little wonder so many people struggle to sleep – and struggle to wake up in the morning.
I’d love to hear your comments about seasonality and day and night. Do you live in an artificial summer all year round?