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Before you crawl into bed tonight, turn out the lights and power down your devices. Exposure to artificial light — from sources such as overhead lights, smartphones and televisions — was associated with higher rates of obesity, according to new research published in JAMA Internal Medicine.
The study included almost 44,000 women between the ages of 35–74 over a six-year period and found women who were exposed to artificial light while sleeping had a 17% higher risk of gaining approximately 11 pounds compared to those who slept in the dark; their rates of obesity were 33% higher. Women who fell asleep with a television or light on were also more apt to gain weight and become overweight or obese over time.
LIGHT AND CIRCADIAN RHYTHM
“Humans are genetically adapted to be active during daylight and sleep in darkness at night,” explains lead author Dr. Yong-Moon (“Mark”) Park, MD, postdoctoral fellow at the National Institutes of Health. “Exposure to light at night while sleeping could alter the body’s 24-hour body clock leading to changes in hormones and other biological processes that regulate sleep, appetite and weight gain.”
While the study focused on exposure to artificial light in the bedroom but Park notes that light coming from outside the room — from other rooms or street lights, for example — was also associated with a slightly increased risk of weight gain. The study did not explore whether overall exposure to artificial light, including daytime exposures, had an impact on weight.
THE SLEEP-WEIGHT CONNECTION
Several studies have linked sleep issues, including insomnia, sleep duration and sleep disruptions, to higher rates of obesity. Research published in the journal Sleep Medicine found the incidence of obesity was higher among those who slept fewer than six hours or more than nine hours per night; chronic insomnia was also associated with higher BMI, according to one study.
The link between sleep and obesity is one reason to make improving sleep a priority, says Lu Qi, MD, PhD, director of the Tulane University Obesity Research Center. But sleep is just one of the known risk factors for obesity. Lifestyle factors such as an unhealthy diet, sedentary lifestyle, stress and smoking are also linked to an increased likelihood of being overweight or obese.
“Even if you improve your sleep habits, you still need to pay attention to other risk factors,” says Qi. “We also need to be cautious in interpreting these results; artificial light might be a factor but it could be correlated to other habits that were not part of this study.”
Park agrees, adding, “While our study provides stronger evidence than other previous studies it is still not conclusive. Even so, it seems reasonable to advise people not to sleep with lights on. Turning off the lights at bedtime may be a simple thing we can do to reduce the chances of gaining weight.”
by Jodi Helmer
While walking is an excellent low to moderately intense workout that’s easy on the joints, you’ll still need to recover properly to improve fitness and avoid injuries. Here, seven steps to include in your post-walk recovery routine:
Whether you’ve gone for a long endurance walk or thrown in some intervals, it’s important to take time to let your body cool down before you head back inside. This allows you to slowly lower your heart rate and get rid of any lactic acid that could potentially cause soreness and a heavy feeling in your legs. A 10-minute walking cool down or completing a few yoga poses are great options post-workout.
One of the most important but often overlooked aspects of recovery is hydration. Even during low-to-moderate intensity workouts, the body loses fluid through sweat that needs to be replaced. If you don’t, recovery takes longer and your performance for your next workout will be negatively affected. In the hour that follows your walking workout, drink plenty of water. If you’re doing long distance training for a walking marathon or have completed a particularly intense workout in hot weather, an electrolyte replacement drink might also be needed. If you’re unsure exactly how much fluid you’ve lost during exercise, weighing yourself before and after workouts is one way you can gauge how much fluid you need to drink to rehydrate properly. You can also track your hydration with an app like MyFitnessPal.
REPLENISH YOUR ENERGY STORES
Consuming healthy, nutrient-rich food after a walk is a must to allow your muscle tissue to repair and get stronger. Skip processed, sugary foods and load up on leafy greens, lean protein like chicken, fish or even a post-workout protein shake.
Stretching as soon as your workout is finished and while your muscles are still warm can help reduce muscle soreness and improve your flexibility — both of which can help you improve your overall fitness and decrease your chances of injury. If you don’t have a ton of time to go through a series of stretches, concentrate on your weak spots. For example, if hamstring tightness is normally an issue, put most of your attention there. When you have the time, try this seated routine that targets many of the common sore spots for walkers.
REDUCE MUSCLE SORENESS
While nutrition and stretching are big pieces to this puzzle, there are other things you can do to help prevent soreness so you can feel better and work out more frequently:
- Massage: This helps improve circulation and relax aching muscles.
- Recovery tools: If you don’t have money or time for a professional massage, try recovery tools like foam rollers, lacrosse balls or a Theragun to loosen up sore spots.
- Ice: Try taking an ice bath or simply icing any sore spots like your knees, lower back or shoulders post-walk.
TRACK YOUR PROGRESS
Setting goals and tracking your progress is an important part of the big picture. Instead of waiting and possibly forgetting about it all together, upload your workout info to your favorite fitness app shortly after you’ve finished your walk. This allows you to see the work you’ve put in and can provide a mental boost when you realize how much you’re progressing.
by Marc Lindsay