Sustainable Culture | Reasons to be Cheerful: The Days are Getting Longer
— January 21, 2013 —
Sustainable Culture is a column by super/collider, exploring the intersection between science, culture and ecology. Please do not print
Spring Sunrise over South Pole Photo by Calee Allen, National Science Foundation.The end of the Mayan calendar seems to have had little effect on planetary systems. Here in the Northern Hemisphere we passed our darkest day on December 21 and thankfully the earth continues to make its yearly voyage encircling the sun.
On the Winter Solstice, Earth’s tilted spinning-axis points towards darkness and distant stellar bodies, as far away from its own light-giving fireball as it can muster. So the northern half of the globe faces the sun for only a short period in its 24-hour rotation. But now, finally, we are past the days of impinging night and by the end of January we are well into the next stage of the cycle, the North Pole is exposing more and more of its icy face to the rays of light and each day is slightly longer than the last.
"By the end of January we are well into the next stage of the cycle, the North Pole is exposing more and more of its icy face to the rays of light and each day is slightly longer than the last"
The number of daylight hours regulates the cycles and rhythms of many living things. Plants decide when to flower based on when the nights get shorter. Animals change the colour of their fur and feathers, and alter their sexual behaviour based on day length. We humans are also affected by the amount of light in our life and scientists have a few different reasons why. One explanation is that our body’s circadian rhythm – the way our body times important biological functions and processes – can be disrupted if we don’t see the light of day. To only see darkness is not that unusual during late December in London when the sun doesn’t even peep over the horizon until after eight in the morning and descends before four each afternoon. If we don’t experience these few hours of light then our body’s cycles are not effectively regulated.
Added to this, scientists think that when daylight streams into our eyes, it passes a signal to the brain to release more serotonin – the chemical that makes you feel really good – and stop making so much melatonin – a sleep-inducing chemical. So it’s all good news for the months ahead, as the days get ever longer, expect heightened moods, deeper sleep and more energy.
Text by Abby Schlageter