Dear Doctors: We’re all pretty stressed-out, even the kids. I keep saying that spending a Saturday in the nice park near our house could help, but my husband just laughs. Isn’t there some kind of research that being outdoors is good for you?

Dear Reader: Just thinking about a walk under the open sky as we began our answer to you brought about a sigh of relief. It makes sense, because long before we humans started spending so much time in built environments, we were deeply connected to the natural world. Many people have an innate understanding about that connection, and years of research backs them up.

Studies show that regularly spending time outdoors confers a host of mental health benefits. These include relief of anxiety and stress, a boost to feelings of calm, enjoyment and well-being, and improvements to mood and attitude. And that’s not taking into account the positive effect that even mild exercise, like walking, has on the body.

It seems like the link between time spent in nature and emotional well-being would be hard to prove, but researchers from the University of Michigan in Ann Arbor found a way. In fact, according to their study, published in 2019 in the journal Frontiers in Psychology, as little as 20 minutes spent outside in nature can have a healing effect. As an added surprise, their study showed the connection holds up even when the green space is in an urban environment.

Over the course of two months, the researchers had 36 volunteers spend at least 10 minutes three times per week in a variety of outdoor environments. These included public parks, the green spaces near their places of work or their own backyards. The participants could either sit still or stroll around during their outdoor time, but they were banned from chatting, reading or using screens of any kind. In order to rule out the known benefits of exercise, they were also asked to refrain from vigorous physical activity prior to their nature walks.

Before and after each outing, samples of saliva, which contains the stress hormone cortisol, were collected from each volunteer. Analysis of the saliva samples revealed that the volunteers returned from their nature outings with lower levels of cortisol than they started out with. Surprisingly, the biggest drops in the stress hormone occurred in the first 20 to 30 minutes of nature immersion. Benefits continued after that, but more gradually. Neither the time of day that someone chose to be outdoors nor where they spent their time played a role in the stress reduction. According to this study, the simple act of stepping outside into a green space began to bring relief.

The time frame that this study reveals is certainly new, but research about the benefits of spending time in nature dates back to the 1970s. We hope that, with proximity to a park and the low bar of 20 to 30 minutes, you’ll be able to persuade your family to make being outdoors a regular part of their lives.

(Send your questions to askthedoctors@mednet.ucla.edu. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctors: Is there more than one kind of COVID-19? I heard on the news about something they’re calling “long COVID,” and it sounds like a whole different kind of disease. How do you get it? Can it be cured?

Dear Reader: It’s true that we’re hearing a lot about long COVID these days. Despite being referred to by a different name than COVID-19, it’s not a separate illness. Rather, long COVID is a term used to describe the lingering symptoms that can affect some people who have survived COVID-19. People who are experiencing long COVID are sometimes referred to as "COVID long-haulers."

As we know all too well by now, COVID-19 is the name of the illness that can arise when someone becomes infected with the novel coronavirus. Cases of COVID-19 run the gamut from mild to moderate to severe to fatal. One of the perils of the disease is that it’s impossible to predict how any one person will react to the infection. Even a moderate case of COVID-19 can be challenging, with symptoms that include high fever, body aches, congestion, difficulty breathing, dizziness, profound fatigue and altered mental status. For many people with moderate to severe COVID-19, the disease runs its course in a month or more. However, tens of thousands of survivors experience long COVID, or long-haul COVID, and some symptoms persist.

For these COVID survivors, recovery is long and rocky, marked by repeated setbacks. Even when the worst of the disease has run its course, other symptoms affect patients for many months. These include persistent fatigue, exhaustion, headache, muscle aches, muscle spasms, erratic heartbeat, depression, low blood pressure after exertion and memory fog. Some patients experience increased blood clotting, which can lead to organ damage.

A recent study published in the Journal of the American Medical Association followed the recovery of 145 patients in their 50s who had experienced moderate to severe COVID-19 symptoms. Researchers found that 87% were left with labored breathing and persistent fatigue for months after the initial disease. Another troubling aspect of long COVID is emerging evidence that it can affect the youngest survivors. About 10% of the more than 11 million coronavirus infections reported in the U.S. thus far have occurred in children, and many experience long-lasting symptoms.

It’s still not clear why some people recover completely from COVID-19, while for others symptoms persist for months. One theory is that, even after someone recovers from the initial disease, fragments of the genetic code of the coronavirus may continue to circulate throughout the body. Although these fragments don’t cause full-on disease, they may continue to trigger an immune system response.

At this time, as with COVID-19, there is no single cure for long COVID. Treatment focuses on managing symptoms. However, it has been recognized as a serious problem. Researchers are now launching studies to discover the biological and immunological causes of long-haul COVID. The hope is to identify any biomarkers that make people susceptible to the syndrome and point to successful treatments.

(Send your questions to askthedoctors@mednet.ucla.edu. Owing to the volume of mail, personal replies cannot be provided.)

Hello again, dear readers, and welcome back to our monthly letters column. Like many of you, we’re adjusting to shorter days and longer nights, and we are gearing up for the challenges of winter. This makes us even more appreciative of your staying in touch.

-- Regarding a column about older adults and falling, a reader from Wallingford, Connecticut, asked us to add an important risk factor to the list. “Distractions were not noted in the article,” he wrote. “Distractions can make a loose carpet, stairs and other obstacles even more dangerous. And distractions are spontaneous, which makes them even more dangerous. ‘Once you take your eye off the ball, get ready for a fall.’" Agreed, and thank you.

On that same topic, a reader asked why we said that even a minor injury from a fall can affect quality of life. Although straining a muscle or twisting an ankle aren’t in the league of a broken bone, they do cause pain, restrict movement and affect mobility. Each of those things makes getting through the day more of a challenge.

-- A reader from Virginia Beach, Virginia, who started a fitness plan with her husband, wonders what qualifies as water. “I don’t love having water early in the day, so I drink several cups of tea, all using the same teabag,” she wrote. “I count the tea as water, but my husband insists only plain water really counts. Do I need to switch?” Although caffeine has a mild diuretic effect, it’s not nearly enough to offset the hydration of a cup of tea. Plus, you’re stretching a single teabag to three cups of tea, so, yes, your morning beverage ritual counts toward your daily water total.

-- A recent column about vitamin D included guidelines for both vitamin supplements and sun exposure. “What about those of us who have had skin cancer, including melanoma, and need to avoid sunlight?” a reader asked. “How much vitamin D should we get from vitamin supplements?” This is important, so we’re happy to repeat our advice: People with any history of skin cancer, or who are at risk for skin cancer, should rely on diet and vitamins for their daily allowance of vitamin D.

-- In response to a column that referenced wigs for cancer patients, a reader from Nags Head, North Carolina, shared a discovery about medical expenses. “I was very surprised to learn wigs are a write-off on the annual returns!” he wrote. “Had we known, my wife probably would have gotten the more expensive natural hair wig she felt better in, rather than the cheaper wig she didn’t really like. Please let your readers know this very important fact.” You’re correct that the costs of a wig for hair loss due to a medical condition, such as alopecia or cancer treatments, are tax deductible.

We’ll close with a reminder that we can’t offer a diagnosis or a second opinion, and we can’t comment on specific treatments or medications. Also, we continue to get requests for previous columns. The good news is that a searchable archive is available online at uexpress.com/ask-the-doctors.

(Send your questions to askthedoctors@mednet.ucla.edu. Owing to the volume of mail, personal replies cannot be provided.)