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Screens have taken over our lives, and we’ve reached a point in our existence where we need a doctor to tell us to get outside. A study done in the mid-1990s showed that we spend about 87% of our time in enclosed buildings, and another 6% in enclosed vehicles. Spending just 7% of our time outdoors might sound like a frighteningly low amount, but a 2019 study showed that things have gotten worse over the past 25 years—we now spend just 2% of our time (94 minutes per week) outdoors. And it’s not just adults: children spend half as much time playing outdoors as their parents did—4 hours per week compared to 8 hours per week.

Spending most of our time indoors is taking a toll on our health. Among adults, rates of depression, poor cardiovascular health, nearsightedness, asthma, and insomnia continue to rise. Childhood rates of mental illness, vitamin D deficiency and rickets, nearsightedness, asthma, and poor cardiovascular fitness have increased significantly in recent years as well, and children reportedly experience symptoms of seasonal affective disorder during summer months simply because they spend most of their day indoors.

Al igual que muchas cosas que hacemos hoy que contrastan con nuestro estilo de vida a medida que evolucionamos, vivir principalmente en interiores ha demostrado tener efectos negativos en nuestra salud. Afortunadamente, parece que hemos tocado fondo en este frente y nos estamos recuperando con éxito. Los médicos de todo el mundo han comenzado a recetar tiempo al aire libre a sus pacientes, con resultados impresionantes. En esta publicación, hablaré sobre cuánto tiempo deberíamos pasar al aire libre, cómo y dónde los médicos prescriben el tiempo al aire libre y las razones científicas por las que estar al aire libre es bueno para nuestra salud.

¿Cuánto tiempo deberíamos pasar al aire libre?

A 2019 study of 19,806 people found that 120 minutes (2 hours) per week was the minimum amount of time we should spend outside in order to experience health benefits. Ratings of good health improved with more time spent outdoors, peaking between 200-300 minutes (3.33-5 hours) per week. Of note: Nearly 60% of respondents, or 11,668 people, spent zero time outdoors each week.

El estudio mostró que no importaba si el tiempo que pasaba al aire libre era en una sesión larga o dividido en períodos más pequeños. Sin embargo, no se incluyeron períodos de solo unos minutos al aire libre cuando realizaba actividades diarias habituales, como caminar desde su automóvil a una tienda. El tiempo al aire libre tenía que ser en “espacios abiertos, incluidos parques, canales y áreas naturales; la costa y las playas; y el campo que incluye tierras de cultivo, bosques, colinas y ríos ".

Según los resultados de este estudio, deberíamos pasar un mínimo de 2 horas a la semana o 17 minutos al día al aire libre en algún tipo de entorno natural (¡los parques urbanos califican!). Para obtener los máximos beneficios para la salud, deberíamos aspirar a entre 28 y 42 minutos por día. Puede parecer un poco tonto o poco natural contar los minutos que pasamos al aire libre, pero tener estas estadísticas basadas en investigaciones ayuda a los proveedores de atención médica a recetar tiempo al aire libre de la misma manera que prescriben medicamentos.

Cómo y dónde los médicos prescriben tiempo al aire libre

Doctors and health educators across the U.S. are prescribing outdoor time through “park prescription” programs. Park Rx America has nearly 500 registered prescribers in 46 U.S. states and Mexico, and Park Rx has registered park prescription programs in 35 states. Park prescription programs include a health or social service provider who encourages their patients or clients to spend time in nature with the goal of improving their health or well-being. The programs often include collaboration between park and public land agencies, healthcare providers, and community partners.

Doctors at all 10 General Practice surgery locations in the Shetland Islands of Scotland are now authorized to prescribe time in nature as part of their patient’s treatment, with the goal of reducing chronic conditions like high blood pressure, anxiety, and depression. The “Nature Prescriptions” project even provides a calendar with creative suggestions about how to spend time outdoors and connect with nature, like noticing the shapes of clouds, following a bumblebee, planting a tree, and eating a three-course meal outdoors.

Dr. Qing Li, a professor at Nippon Medical School in Tokyo, has done extensive research on the Japanese practice of shinrin-yoku, or “forest bathing.” Thanks to his research, forest bathing is now mainstream in Japan. The country has designated more than 60 forest bathing spots, many within densely populated cities, which are used by up to 5 million people a year. A growing number of doctors are becoming certified to practice “forest medicine,” and Japanese companies regularly send their employees to forests to rest and reduce their stress.

Si las tendencias continúan, es posible que comencemos a ver anuncios reales como estos videos falsos de Nature Rx, una organización sin fines de lucro con sede en Colorado.

Por qué estar al aire libre es bueno para nuestra salud

Being outdoors exposes us to natural, full spectrum light. Natural light benefits us in three important ways: it increases our production of serotonin, it regulates our circadian rhythms, and it improves our eyesight.

  • Serotonin is a neurotransmitter that plays a role in mood and social behavior, cognition and learning, appetite and digestion, sleep, memory, and sexual desire and function. The more full spectrum light we’re exposed to, the more serotonin we produce. Serotonin production is one of the reasons why bright light therapy (BLT) is now used to treat seasonal and non-seasonal depression. Serotonin is also a melatonin precursor; it gets converted to melatonin in darkness and helps to regulate our sleep-wake cycle.

  • Exposure to natural light each day regulates our circadian rhythms. Circadian rhythms are most often associated with our sleep-wake cycle, but they also affect hormone production, appetite, core body temperature, brain wave activity, cell regeneration, and other biological activities. If you’re looking to improve your sleep, research shows that getting outdoors in the morning is best. Being exposed to natural light or very bright artificial light in the morning advances our circadian clock, stimulating melatonin production earlier in the evening and making it easier to fall asleep at night. Daylight exposure later in the day has not been shown to have the same positive effects on circadian rhythms.

  • Exposure to natural light is protective against myopia (nearsightedness), while computer, phone, and TV screens and fluorescent light can cause eye strain. Researchers believe that the ways in which natural light affects vitamin D and dopamine production play a role in eyesight development, and that this is why too little natural light exposure during childhood can lead to nearsightedness .

Being exposed to sunlight makes our skin produce vitamin D. Getting enough vitamin D is essential for overall health. We need vitamin D so that we can absorb calcium, and so that calcium and phosphorus can be used to build our bones. Vitamin D also plays a role in protecting against and possibly helping to treat the following conditions:

  • Enfermedad cardíaca y presión arterial alta.
  • Diabetes
  • Infecciones y trastornos del sistema inmunológico.
  • Algunos tipos de cáncer, como los de colon, próstata y mama
  • Esclerosis múltiple
  • Fatiga
  • Dolor de huesos
  • Debilidad muscular, dolores musculares o calambres musculares.
  • Cambios de humor, como depresión

Estar expuesto al sol durante aproximadamente 15-20 minutos tres veces por semana suele ser suficiente para que nuestra piel produzca la vitamina D que necesitamos. Pero hay algunos factores importantes a tener en cuenta. La vitamina D se produce cuando nuestra piel se expone a la radiación ultravioleta B (UV-B) del sol. Dependiendo de dónde viva, es posible que la luz UV-B no lo alcance durante ciertas épocas del año. La luz UV-B suele ser más potente entre 10:00am y 3:00pm. La cubierta de nubes y la contaminación del aire pueden disminuir la cantidad de luz UV-B que pasa. Y cuanto más oscura sea su piel, se necesita más exposición al sol para producir suficiente vitamina D.

As we know, sun exposure is safest in moderation. You can refer to this chart, known as the Fitzpatrick scale, to see how much exposure is safe based on your skin type. Always wear sunblock if you’ll be exposed to the sun for a long period of time, and make sure to avoid getting sunburns.

Spending time in forests exposes us to phytoncides and enhances human natural killer (NK) cell activity. Natural killer (NK) cells are part of our immune system’s first line of defense, reacting rapidly to infected and dangerous cells, including cancer cells. And what are phytoncides, you ask? They’re antimicrobial compounds that are naturally emitted by trees and other plants. Scientists speculate that one reason forest bathing strengthens the immune system is because of exposure to phytoncides.

To test this theory, Dr. Qing Li put 12 healthy men in hotel rooms overnight for three nights. Phytoncides were produced in the rooms by vaporizing cypress stem oil with humidifiers, and the concentrations of phytoncides were measured. Phytoncide exposure significantly increased natural killer (NK) activity and levels of anti-cancer proteins, and decreased the concentrations of adrenaline and noradrenaline (stress hormones) in urine. This results of study and others that have tested the effects of forest bathing on immune system function indicate that phytoncide exposure and decreased stress hormone levels may partially contribute to increased NK cell activity.

Being near moving water exposes us to high levels of negative ions. If you don’t live near a body of water, you can expose yourself to naturally occurring negative ions by taking a shower or going outside right after it rains. As water breaks up into small droplets, electrons combine with oxygen molecules in the air to form negative-ion clusters.

Scientists have been speculating since the 1950s that negative ions stimulate the relaxation response of the parasympathetic nervous system. A 2005 study found that water-generated negative ions enhance NK cell activity, inhibit the initial formation of cancer, and suppress tumor growth in mice. Other studies have found positive effects of negative ion exposure in treating seasonal affective disorder and chronic depression. While there isn’t a great deal of consistent research on negative ions, it’s a topic that warrants exploration.

¿Listo para su receta natural?

If you don’t currently spend much time outdoors, start by aiming for 20 minutes per day. This will get you to the threshold of 2 hours per week that has been found beneficial for overall health, and will likely provide you with enough vitamin D. The stress hormone cortisol also drops significantly after spending just 20 minutes outdoors in a natural environment.

The good news is you don’t need to plan a forest bathing trip to Japan to reap the benefits of going outside. A review of 143 studies found that living near or spending time in “greenspace” like parks was enough to improve health. The researchers found that stress, heart rate, blood pressure, cholesterol, type II diabetes, stroke, hypertension, asthma, heart disease, and cancer were all lower among people who were exposed to greenspace. A study of 345,143 people found that those who lived within 1 km of greenspace had lower rates of 15 of 24 disease clusters, most significantly anxiety and depression. And a study of 31,000 Toronto residents found that having an average of 11 more trees in a city block improved cardiovascular and metabolic health in ways comparable to an increase in annual personal income of $20,000.

¿Quieres salir más al aire libre, pero no sabes cómo encajarlo en tu horario? Empiece por pensar en formas en las que puede realizar sus actividades diarias habituales al aire libre, como:

  • Comer al aire libre
  • Toma descansos en el trabajo afuera
  • Haz tus entrenamientos al aire libre
  • Camine o vaya en bicicleta al trabajo (si su viaje al trabajo es demasiado largo, intente caminar hasta una tienda o restaurante local)
  • Juega con tus hijos afuera
  • Toma tu computadora portátil y trabaja afuera
  • Take phone or in-person meetings outside
  • Relájese al aire libre (lea, hable con un amigo o incluso mire su teléfono) en lugar de mirar televisión en el interior

En poco tiempo, salir al aire libre será parte de su rutina habitual. Una vez que comiences a sentir el impulso inmediato en el estado de ánimo y la energía que obtienes al salir, comenzarás a esperarlo e incluso a desearlo. Un paseo rápido al aire libre puede reemplazar a una taza de café (en serio). ¡Nos vemos ahí fuera!

Lectura recomendada:

The Pain Relief Secret: How to Retrain Your Nervous System, Heal Your Body, and Overcome Chronic Pain by Sarah Warren, CSE

Somatics: Reawakening the Mind’s Control of Movement, Flexibility and Health by Thomas Hanna