A good night’s sleep can improve your mood, help you stay alert and boost your memory. Now data show that getting enough Z’s might also get your cuts to heal more promptly. In fact, sleep was more important than good nutrition in speeding wound healing.
This wasn’t what scientists had expected to see.
They had hoped to show that giving people a nutritional boost would make their skin wounds heal faster — even in people who were sleep-deprived. That would have been useful for soldiers in combat, or for doctors working long shifts in a hospital. The scientists thought it should work because good nutrition keeps the body’s immune system strong. That immune system helps repair injuries and guards against infection.
Tracey Smith is a nutrition scientist at the U.S. Army Research Institute of Environmental Medicine, in Natick, Mass. She and her team studied three groups of healthy people who came to their laboratory to take part in tests. They gave each recruit small skin wounds. Applying gentle suction on their forearms, they created blisters. Then they removed the tops of these blisters. (The procedure doesn’t hurt, although it can be itchy, Smith says.)
One group of 16 volunteers got a normal amount of sleep — seven to nine hours a night. The other two groups of 20 people each were kept sleep deprived. They got only two hours of sleep a night, for three nights in a row. To stay awake, the volunteers were asked to do things such as walk, play video games, watch TV, sit on an exercise ball or play ping-pong. Throughout the experiment, one of the sleep-deprived groups got a nutritional drink with extra protein and vitamins. The other group got a placebo drink: It looked and tasted the same but had no extra nutrition.
Sleep clearly helped. People who slept normally healed in about 4.2 days. The sleep-deprived volunteers took about 5 days to heal.
And getting better nutrition offered no clear benefit. Scientists sampled fluid from the wounds. The group that drank the nutritional supplement did show a stronger immune response at the wound. But that didn’t speed the healing, Smith reports in the January Journal of Applied Physiology.
What to make of the data
Sleep expert Clete Kushida didn’t find the results all that surprising. He is a neurologist at Stanford University Medical Center in California. The idea that lost sleep harms the immune system — and healing — “makes total sense,” he says. Yet studies that have tried to test this in people and animals showed mixed results.
Why didn’t nutrition help healing time? Smith can think of a few possibilities. The healthy drinks may have helped a little — just not enough to show up clearly in the relatively small numbers of men and women tested here. There was also a big difference in healing time between individual participants, which could have made it harder to see a small effect due to nutrition.
For people who can’t avoid lost sleep, scientists still don’t have a nutritional way to help them heal, Smith says. If you want to heal faster, your best bet for now is to get more “vitamin Z.”
immune (adj.) Having to do with the immunity. (v.) Able to ward off a particular infection. Alternatively, this term can be used to mean an organism shows no impacts from exposure to a particular poison or process. More generally, the term may signal that something cannot be hurt by a particular drug, disease or chemical.
immune system The collection of cells and their responses that help the body fight off infections and deal with foreign substances that may provoke allergies.
infection A disease that can spread from one organism to another. It’s usually caused by some type of germ.
neurology A research field that studies the anatomy and function of the brain and nerves. People who work in this field are known as neurologists (if they are medical doctors) or neuroscientists if they are researchers with a PhD.
nutrition (adj. nutritious) The healthful components (nutrients) in the diet — such as proteins, fats, vitamins and minerals — that the body uses to grow and to fuel its processes. A scientist who works in this field is known as a nutritionist.
placebo A substance that has no therapeutic effect, used as a control in testing new drugs.
protein A compound made from one or more long chains of amino acids. Proteins are an essential part of all living organisms. They form the basis of living cells, muscle and tissues; they also do the work inside of cells. Among the better-known, stand-alone proteins are the hemoglobin (in blood) and the antibodies (also in blood) that attempt to fight infections. Medicines frequently work by latching onto proteins.
statistics The practice or science of collecting and analyzing numerical data in large quantities and interpreting their meaning. Much of this work involves reducing errors that might be attributable to random variation. A professional who works in this field is called a statistician.
supplement (in nutrition) Something taken in pill or liquid form — often a vitamin or mineral — to improve the diet. For instance, it may provide more of some nutrient that is believed to benefit health.
vitamin Any of a group of chemicals that are essential for normal growth and nutrition and are required in small quantities in the diet because either they cannot be made by the body or the body cannot easily make them in sufficient amounts to support health.
Journal: Tracey J. Smith et al. Impact of sleep restriction on local immune response and skin barrier restoration with and without ‘multi-nutrient’ nutrition intervention. Journal of Applied Physiology. Vol. 124, January 2018, p. 190. doi: 10.1152/japplphysiol.00547.2017.