How Sleep Strengthens Your Immune System


Adults need a minimum of seven hours sleep every night for improved health and well-being.

In 2016 the Centers for Disease Control and Prevention concluded that more than one-third of Americans weren’t getting enough sleep.

Kimberley Hardin, MD, director of the sleep medicine fellowship program at the University of California Davis, says many people take good sleep for granted.

“People underestimate the importance of sleep, and less than seven hours per night on a regular basis has negative effects. It essentially creates a fight-or-flight state, with increased stress hormones and release of adrenaline,” she told Healthline.

“Sleep is like anything else in the body,” Dr. Hardin said. “It’s a natural state and has to be taken care of to be healthy. Sleep should leave you feeling refreshed, not groggy and struggling. Realistic expectations are essential. And sleep changes as you age, so you may not feel as rested as you did when you were a younger.”


Less than five hours sleep per night on a regular basis is associated with higher mortality, and having less than seven hours sleep for three nights in a row has the same effect on the body as missing one full night of sleep.

And poor sleep can have both short-term and long-term health consequences.

“Bad sleep can result in long-term problems with mood, memory, and blood sugar, among other things,” Suzanne Stevens, MD, a sleep neurologist at the University of Kansas Health System, told Healthline. “Short-term consequences of bad sleep may include sleepiness, poor judgment, car accidents, moodiness, memory problems, workplace mistakes, and more. Chronic poor sleep affects not only the ability to function well the next day, but the sleep deficit builds up the longer sleep isn’t good.”

Inside the body, chronically bad sleep can cause problems.

Poor sleep can increase inflammation, blood pressure, insulin resistance, cortisol, weight gain, and cardiovascular disease, as well as decrease blood sugar regulation.

A good night’s sleep is also thought to be protective against heart disease. A 2019 study in mice found a connection between the brain, bone marrow, and blood vessels that protects against hardening of the arteries. This mechanism only took place in mice who had a good quality sleep.

Researchers are hopeful that an understanding of the link between sleep and cardiovascular health will pave the way for new treatment options.