With the transition to solar time, which occurred between Saturday 25th and Sunday 26th October, the clock hands moved back by an hour, reducing the hours of evening light in our days, which will progressively shorten until the winter solstice. This change can affect our mood, making us feel more tired and down in the dumps, while at high latitudes the arrival of the polar night, in which the sun does not fully rise for months, can cause real episodes of seasonal depression. In fact, if on the one hand the cold and early evening change our lifestyles, on the other the reduced availability of light affects the production of key molecules for our well-being and mood, such as melatonin and serotonin. All these mechanisms together could explain the decline in our mood in winter, a frequent phenomenon especially in Nordic countries and which according to some evolutionary theories could have represented a winning strategy for our ancestors who lived thousands of years ago.
Does sunlight affect our mood? The case of the Finnish Kaamosmasennus
Have you ever felt a little down in the dumps or more heavy during periods of the year when it gets dark early? If the answer is yes, you are not alone at all. For many of us, in fact, the progressive shortening of the days until the winter solstice is often accompanied by a drop in mood and a feeling of greater tiredness. And, as if that wasn’t enough, the transition from summer time to standard time at the end of October “steals” an additional hour of evening light, making the days even shorter.
Yet, we Italians, like the inhabitants of the southernmost countries of Europe, can consider ourselves lucky. In Finland, for example, between the end of November and January there is kaamos, the so-called “polar night”, during which the sun never goes above the horizon and the days oscillate between twilight and total darkness. Precisely in this period, many Finns experience a real form of seasonal depression characterized by a general decline in mood and an increase in the feeling of tiredness. A condition so widespread that it has taken the name of kaamosmasennus (literally “winter depression”), which many studies correlate with poor exposure to sunlight.
Italians prefer days with more hours of evening light
In Italy, fortunately, we do not have to face anything comparable to the Finnish kaamos. Yet, even here the days are drastically shorter with the arrival of autumn and winter. To give a concrete example, in Naples in June the sun sets around 8.30pm, giving us more than 15 hours of light; at the end of December, however, the sky begins to darken around 4.30pm, giving us just over 9 hours of sunshine.
But do Italians prefer the long summer days or the twilight ones typical of winter? According to a survey conducted in 2019 by the YouGov platform, on the occasion of the European Parliament’s proposal to abolish the time change, out of a sample of 1007 interviewees, 69% declared themselves in favor of the permanent adoption of summer time, with the aim of having more hours of evening light available in winter. A change, according to 62% of those interviewed, also motivated by the expectation of an improvement in mood resulting from the lengthening of the days.
Is there any scientific basis or is it just suggestion?
Certainly having more hours of light during the day allows us to spend more time outdoors, carry out physical activity and maintain a more active social life, all activities known to “recharge” our mood and general well-being.
However, sunlight can have a much more direct influence on our bodies, influencing our neurobiology. In the retina, scattered among the cells that allow us to see shapes and colors, there are cells that act as actual “light sensors”. They are called intrinsically photosensitive retinal ganglion cells and work in a similar way to those lamps that turn on automatically as soon as they detect a situation of environmental darkness.
In fact, when dusk falls, these cells send a signal that warns the brain of the arrival of darkness, which in response stimulates the production of melatonin, the hormone that promotes sleep. And since the days are shorter in winter, melatonin secretion starts earlier and lasts longer, helping to make us feel more sleepy. At the same time, light, through the same cells, influences the natural production cycle of serotonin, the famous “good mood molecule”. It is no coincidence that some studies have observed anomalous variations in the levels of these molecules in people suffering from seasonal depression, a more common disorder during the cold months and with fewer hours of sunshine, and often treated effectively through light therapy.
If we are more tired in winter it is all the “fault” of evolution
Having reached this point, a question arises spontaneously: why does our biology seem to “hinder us” in the cold seasons, when the availability of ambient light is less? The answer, as often happens, must be sought in our past.
Our lifestyles have changed radically in the last two centuries, but our organism has evolved over millions of years, adapting to environmental conditions that are very different from those we experience today. And before the invention of light bulbs, cities and heating systems, the arrival of winter and the shortening of the days meant exposing oneself to predators and invisible nocturnal dangers, facing severe famines and freezing temperatures, all situations capable of seriously putting one’s life at risk.
But biology may “have found a solution”: making us slow down and feel sadder and more apathetic during the coldest, darkest times of the year. A strategy that might seem inconvenient today, but which for thousands of years may have defended us from the dangers of the harshest periods of the year, saving energy to face the challenges that come with the long, bright days of spring.
