Dear Doctor: I saw on the news that if you work out for 11 minutes a day, you are protected from the bad stuff that happens from sitting too much. Is that really true? I’m stuck at my desk all day, and that’s not changing anytime soon.

Dear Reader: We think you’re referring to a recent study, published in the British Journal of Sports Medicine, which looked at the health outcomes of people whose lifestyles ranged from extremely sedentary to moderately active. According to the findings, even a small amount of daily exercise helped to mitigate the negative health effects of prolonged inactivity.

The conclusions outlined in the study caused quite a splash and have since popped up on TV, newspapers and magazines. And small wonder: Several years ago, research linked prolonged sitting -- that’s eight hours or more per day -- to an increased risk of premature death. With so many jobs, like your own, now tethering workers to their desks, people have become eager for information on how to lessen the ill effects.

This new research, which reexamines data collected in nine previous studies, focused on about 44,000 people who each wore an activity tracker to accurately monitor their daily movement. The participants, who were middle-aged and older, remained seated an average of 10 hours each day. When they did exercise, it consisted of short sessions -- eight to 35 minutes -- often simply walking at a moderate pace.

When the researchers looked at mortality rates in the years after the participants enrolled in the studies, they found the expected link between the people who exercised the least and an increased risk of premature death. The surprise came when quantifying just how much exercise it took to reverse the trend toward an earlier death. The answer was the 11 minutes of daily exercise that grabbed your attention in the news story you saw. It’s important to note that those 11 minutes of exercise did not, as you said in your question, completely erase the ill effects of prolonged sitting. However, the findings of the study do suggest that even a small amount of exercise appears to confer health benefits.

An important conclusion in the study, which headline writers didn’t get quite so excited about, is that the magic number when it comes to exercise appears to be 35. That is, the greatest benefit comes when someone engages in moderate exercise for at least 35 minutes per day. That’s actually in line with the current guidelines put forth by the Department of Health and Human Services. Specifically, at least 150 minutes of moderate aerobic activity, or 75 minutes of vigorous aerobic activity, spread out over the course of a week. Interestingly, several studies have suggested that those 35 minutes of exercise don’t have to happen all at once. Rather, they can be split up into several sessions throughout the day and still yield a similar benefit. That’s encouraging news for people who think they don’t have time to exercise. Let’s all celebrate by getting up out of our chairs right now and taking a brisk 10-minute walk.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: My boyfriend and I live in northern Ohio, and I think we have that thing where you get depressed from not enough light. He’s kind of skeptical, but I really do think it’s happening. Can you describe the symptoms? Is there anything we can do?

Dear Reader: You’re referring to a condition known as seasonal affective disorder, or SAD. Sometimes referred to as the winter blues, it’s a mental health condition that has been linked to the shorter days and longer nights of the fall and winter seasons. Although the exact causes aren’t yet known, researchers have explored several hypotheses. These include the idea that reduced levels of sunlight have an adverse effect on circadian rhythms, on levels of the brain chemical serotonin or on the hormone melatonin.

There’s also a link between distance from the equator and incidences of SAD. People living in the northern reaches of the United States, as you do, are at greater risk of developing SAD than those in the southern part of the country.

It’s estimated that up to 20 million people in the U.S. experience some degree of seasonally related depression each year. Symptoms often begin with autumn’s annual double whammy of shortening days and the end of Daylight Saving Time. They intensify throughout the darker months of winter, then ease up again in the spring. Symptoms include persistent low mood, lethargy, lack of energy, sleep disruption, irritability, loss of interest in daily activities, feelings of hopelessness, difficulty concentrating, anxiety or weight gain. Episodes of SAD can begin with symptoms that are mild, but which gradually intensify. In some cases, symptoms can become severe enough to interfere with daily life.

If you suspect you may be experiencing seasonal affective disorder, you should see your health care provider. Several other medical issues, such as thyroid conditions, anemia or clinical depression, can present with symptoms similar to SAD. Diagnosis involves a physical exam, including a detailed discussion about symptoms relating to mental health. In order to rule out thyroid issues, a blood test may be performed.

For people diagnosed with SAD, treatment can include light therapy, psychotherapy or medication. Light therapy is just like it sounds -- deliberate exposure to bright light. The individual sits in front of a specially designed light box for 30 to 45 minutes each day. These devices are made to filter out damaging UV rays. However, since they are up to 20 times brighter than natural light, they may not be right for everyone. People with certain eye conditions, or who take medications that increase sensitivity to light, must be under medical supervision to use light therapy. Psychotherapy, or “talk therapy,” offers a time and place to share feelings and to learn coping techniques. Medications that affect serotonin metabolism can also be helpful.

Meanwhile, be kind to yourself. Try to spend some time outdoors each day, get regular exercise and eat a healthful diet. Keep screen time to a minimum. And if symptoms persist when the sunlight returns, be sure to tell your doctor.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: Our family -- ages 66, 59, 27 and 22 -- lives in one household. We’ve been working from home and keeping socially distant since the start of the pandemic. Now the younger members wish to resume outside employment. How do we safely manage their return to work?

Dear Reader: The challenge in multi-generational households like yours is keeping the older members safe. The answer lies in the basic precautions we’ve learned to take during this pandemic, along with an added layer of vigilance and awareness. We may sound like a broken record by now, but that means wear a mask, maintain distance from people outside of your household and be consistent about washing your hands. We tell our patients to assume that each time they leave their homes, they will encounter someone infected with the coronavirus, and to behave accordingly. Considering the spiking infections across the nation at this time, that’s not an exaggeration.

When it comes to the younger people spending time outside the family bubble, you’re talking about an increased level of risk. Any risks they take outside of the home, they bring home with them. While in the workplace, they need to wear a good mask at all times, and continue social distancing as much as possible. The fabric of a mask not only limits the distance someone’s breath will travel, it also provides a physical barrier that can protect the wearer as well. That’s important because we now know that some transmission of the coronavirus is airborne. We also know that some individuals can be infected with the virus but have either no symptoms or symptoms that are quite mild. They’re lucky enough not to feel sick, but, unfortunately, they are still able to pass the virus along to other people, who may become quite ill.

Physical distancing remains important. Studies have made a connection between viral load, which is the concentration of virus someone is exposed to, and the severity of subsequent infection. The further away you stand from someone, the less their exhaled breath can reach you. When combined with a mask, social distancing can measurably reduce your risk of coming into contact with the virus. And, because viral particles can also be carried via droplets that land and persist on surfaces, washing or sanitizing your hands, as well as high-touch surfaces, remains important.

Your family should discuss their comfort with risk, then decide the steps to take to address it. This can include no physical contact, sequestering in different parts of the home and even wearing masks in each other’s presence. Ventilation is important, so if your climate allows, keep windows and doors open, and spend time together outdoors. Remain alert for COVID-19 symptoms, which include fever, chills, exhaustion, difficulty breathing, headache, gastric upset and sudden loss of taste or smell. If someone begins to feel unwell, or has contact with an infected source, they should isolate from the rest of the family immediately to prevent spread. If you follow these measures and don’t let your guard down, the risk of infection and transmission will remain low.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)