The Science Behind Spring: Why We Feel Happier When the Weather Warms Up

As a long, depressing winter season slowly starts to thaw, many people might think of the same question: “How long until the arrival of spring?” Although some individuals are familiar with the term “seasonal depression” and are aware that the feelings associated with winter greatly contrast those associated with the arrival of warmer seasons, not many know the science behind how the onset of a warmer season can so drastically impact our mood. 

“Seasonal depression,”—more scientifically known as Seasonal Affective Disorder (SAD)—is a type of depression most commonly associated with the arrival of colder seasons, such as fall or winter. According to The American Psychiatric Association (APA), this condition is affects nearly 38 percent of Americans during colder months. Additionally, among the individuals polled, two-thirds stated that they have experienced shifts in mood, indicating that although not all people may be outright depressed, the majority do note a significant emotional change. The biggest link scientists can make to this shift in mood is the fact that colder seasons result in less sunlight. This lack of sunlight affects an individual’s mood by increasing daytime drowsiness, causing excessive fatigue, and increasing appetite—specifically for sweets and carbs, to name a few. On the other hand, the beginning of spring combats all of these symptoms by reversing the main cause of SAD and causing more sunlight.

One way sunlight directly influences an individual’s body and reverses SAD is by producing more serotonin—the body’s “feel-good” neurotransmitter. Sunlight enters through the eyes and stimulates parts of the retina, causing the brain to produce serotonin. Serotonin functions by carrying messages between two nerve cells, signaling the body to conduct a wide variety of functions, such as regulating mood to feel more focused and happy, getting rid of irritating foods or toxins in the gut, and increasing sleep quality. All of these functions contribute to a person’s overall well-being, which explains why sunlight makes us happier. 

Contrastingly, as the amount of sunlight increases, the body’s production of melatonin—also known as the body’s “sleep hormone”—decreases. Melatonin is a hormone produced by the pineal gland of the brain and is responsible for the body’s sleep-wake cycle by stimulating the body to get ready for sleep. Production of melatonin occurs when the body is surrounded by darkness rather than light, which explains why melatonin production and consequent drowsiness are greater during colder months when days are shorter and nights are longer. This also explains why people are generally more productive during warmer months like spring; there is a lack of melatonin present during the day, promoting activity rather than fatigue. 

Sunlight not only has effects on the human body through hormones and neurotransmitters but also psychologically. The beginning of spring is associated with the blooming of bright colors, such as green, yellow, and pink. Some of the flowers that bloom are pastel shades of certain colors, which color analysts show promote a light, calming feeling, contributing to overall happiness. In particular, the color green is fascinating to many psychologists, since it is linked to many positive, rejuvenating feelings such as improved memory and positive thinking. This is because the color green has a strong association with calmness and positive emotions, which relaxes the brain and aids in cognitive function. Studies have also shown that spending more time around nature, particularly trees, reduces stress by aiding in the reduction of cortisol—a stress hormone—and blood pressure. The reduction of cortisol greatly contributes to better mental health by causing positive feelings.

Lastly, warmer weather encourages outdoor activities, such as walking, hiking, and exercising in fresh air. This not only helps with physical activity but also promotes positive mental health. Exercising is known to release endorphins—special chemicals in the brain that act as natural antidepressants—uplifting mood. Being outdoors also promotes vitamin-D absorption in the body—a process that regulates mood and sleep by affecting levels of both serotonin and melatonin. 

The happiness that comes with the arrival of spring is not just a feeling; it is rooted in biology and psychology. As a result, some mental health complications may arise in certain geographical areas where warmer, sunnier months are less prevalent and SAD-inducing seasons are more common. On the bright side, technology is working to help those in need of positivity in gloomy months. For example, sun lamps—also known as SAD lamps or light therapy boxes—artificially create sunlight, replicating the effects that sunlight evokes in a person’s body, such as the aforementioned serotonin and melatonin levels. Although these inventions exist, it is still important not to take the presence of warmer seasons such as spring for granted. Spend more time outdoors to reap the benefits of the sun and improve mental health. The return of sunlight means more than warmth; it means emotional renewal.