Friday, September 29, 2023

Why, despite the heat, our brain likes summer

We republished this article by José Á. Morales García, scientific researcher in neurodegenerative diseases and professor at the Faculty of Medicine of the Complutense University of Madrid (UCM), published in The Conversation on August 24, 2023.

Said the American writer Ursula K. LeGuin that “when you light a candle, you also cast a shadow”. That is to say, there are two opposite poles of everything, yin and yang, and balance arises precisely from that dichotomy.

When the heat is pressing, the temperature balance is maintained thanks to the thermoregulation. But no matter how hard the hypothalamus works, the region of the brain responsible for keeping us at a constant temperature all year round, when the body reaches temperatures above 40ºC there is no way to resist. AND the heat ends up having negative effects on the nervous system.

Obviously, one of the parts most sensitive to extreme heat is the brain. The loss of salts and fluids can cause us to suffer from exhaustion, dizziness, nausea, and excessive sweating. Or heat stress, which decreases alertness, memory, or motor coordination. Not to mention sleep disorders, which in addition to fatigue and daytime sleepiness delight us with a wonderful state of irritability. In the worst case we can suffer a heat stroke, and here things get serious, because it can kill us.

This is the yin of summer. But is there yang? Can we find something positive in the arrival of the warm months? There has to be, because otherwise there would be no balance. Summer brings numerous benefits to our body, and everything that is good for the body is good for the brain.

Livelier with increased serotonin

Summer brings more daylight hours, and that means more production of serotonin, the neurotransmitter that allows certain neurons to communicate with each other. The result of this communication is very varied, since serotonin influences the moods, learning, memory, body temperature regulation, sleep, sexual behavior, or hunger. With this variety of functions, it is logical to think that abnormal amounts of this neurotransmitter can cause alterations.

For example, low levels Serotonin levels are associated with depression, anxiety, sleep problems, obsessive-compulsive disorder, schizophrenia, or various phobias. And when circulates too much we find tremors, excessive sweating, confusion, restlessness, high blood pressure or spasms.

For this reason, let us stay with the words of Aristotle: “virtue is in the middle ground”. And it is that, in its proper measure, serotonin positively influences our mood. This is where summer comes in, as sunlight promotes the binding of this neurotransmitter (like a key) with its 5-HT1A receptor (the lock) in brain regions that control emotions. And in this way, it improves our mood. Not in vain is it one of the so-called “molecules of happiness”.

Sunbathing (with caution) also benefits the brain

But the human being lives not only on serotonin: sunlight also brings other benefits. For example, it stimulates production of vitamin Dwhich among other things improves neuronal health and prevents neurodegenerative diseases.

When sunlight falls on our skin, keratinocytes (the most abundant cells in the epidermis) produce this compound, which is necessary for the proper functioning of the brain. And since everything is ultimately related, vitamin D generated in the skin by sunlight also increases levels of the serotonin precursor and transporter. Or, put another way, vitamin D promotes the formation of serotonin.

At this point it is convenient to remember two things. The first, that for the skin to produce vitamin D it is necessary to be exposed to direct sunlight. That is, if we are at home with the window closed, it will not stimulate its production. Second, although the use of sun creams decreases the production of vitamin D, sunbathing without protection promotes the appearance of skin cancer. Remember that to activate the synthesis of vitamin D, fifteen minutes is enough.

Proximity to the sea, guarantee of happiness

Another of the joys that summer brings us are the pools and the sea, and with them swimming. This complete activity not only brings us physical benefits, but also mental: it helps to fight against oxidative stress and free radicals, stimulating our immune system and improving our cognitive capacity and memory.

If swimming is good, imagine doing it in the sea, which produces positive effects about him immune system, cardiovascular and mood. Because the sea is synonymous with vacations, for our body and mind.

In big cities we live surrounded by a chaos of stimuli that overexcite our brain. On the other hand, spending time near the ocean can help us relax and reduce stress and anxiety levels. The sound of the waves, the sea breeze and the color of the water have a relaxing effect that decreases cortisol levels and sympathetic nervous activity. be by the sea increases the secretion of serotonin and endorphins, which produce a feeling of happiness and tranquility.

In summary, our brain likes summeralso perhaps because it promotes a social connection that brings enormous benefits to our mental health.

There is still summer ahead, so, as the song says, “Let the sunshine, let the sunshine in, the sunshine in…”.

The Conversation


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