How Sleep Deprivation Affects the Brain and Body

We’ve all heard the age-old recommendation of getting seven to nine hours of sleep per night. Perhaps you need more than that, and maybe you can get by with less—but if you fall below your "magic" minimum number, your body and brain will most likely protest in various ways throughout the day.

Clinical sleep educator and registered nurs Terry Cralle says there are countless reasons to prioritize sleep. "It impacts so many aspects of our functioning: health, well-being, performance, our ability to reach our full potential and, ultimately, quality of life. It impacts our mood, our outlook, how we handle stress, how we problem-solve, our motivation, our judgment, memory—all things that affect our successes and achievements."

According to statistics from the American Sleep Association, more than 35 percent of adults get less than seven hours of sleep during a 24-hour period. And the effects can go far beyond feeling sleepy or short-tempered; sleep deprivation can have a ripple effect into all areas of your physical and mental wellness.

Lack of focus

When you haven’t had adequate sleep, Cralle says it is more difficult to focus. This can affect not only performance in the workplace and at school, but also when doing gravely important things like driving a car, performing a medical procedure or making important financial decisions.

"We are more clumsy and uncoordinated when we are sleep-deprived, and our reaction times are slower," notes Cralle. "Our risk of on-the-job accidents is increased without sufficient sleep, as well as the risk of car crashes and athletic injuries."

Reduced job satisfaction and performance

Sleep deprivation can compromise productivity in all areas of life. Studies show that when we’re tired, we are more likely to procrastinate or engage in "cyberloafing," warns Cralle. She adds that research published in 2006 found that insomnia was negatively related to job satisfaction and associated with increased feelings of hostility, fatigue and inattentiveness. "Work attendance, work performance and healthcare costs are all negatively impacted by employees who have trouble sleeping," Cralle notes.

Weaker immunity

The immune system releases proteins called cytokines during sleep, which need to increase when we are under stress or have an infection or inflammation, says Cralle. When we get insufficient sleep, it leads to a lower production of these protective cytokines, along with infection-fighting cells and antibodies.

Impaired stress management

Sleep deprivation increases the production of the stress hormone cortisol, which means we are less able to handle stress when we don’t get enough shuteye, notes Cralle. "We can't manage stress, occupational burnout or related issues unless we manage sleep," she says. "Because of the cause-and-effect relationship between stress and sleep, sufficient sleep must be the first consideration in an attempt to prevent, manage or mitigate stress."

Increased heart disease risk

Poor sleep can cause increased blood pressure at night, higher core temperature and often refractory blood pressure in the morning, says Dr. Heather Hammerstedt with Wholist Health. "This has been shown to increase risk for heart attack, cardiovascular death, vasospasm and decreased exercise recovery time," she warns.

Increased cancer risk

Cralle points out that sleep-deprived people may be more susceptible to developing certain types of cancers. Studies have identified a relationship between a lack of sufficient sleep and breast, prostate and colorectal cancers. Another study demonstrated an association between insufficient sleep and biologically more aggressive tumors, as well as the likelihood of cancer recurrence in postmenopausal women.

Increased risk of obesity

Your sleep (or lack thereof) could be to blame for your cravings, unhealthy food choices and weight gain, says Cralle. "Numerous research studies have shown that sleep deprivation plays a major role in weight gain and obesity, negatively affecting hormones that are key to healthy weight management," she warns.

Insufficient sleep has been tied to increased appetite, metabolic changes, unhealthy food choices (we reach for foods high in fats and sugar to help us stay awake) and lack of energy or motivation to exercise—all factors that contribute to weight gain.

In addition, Cralle adds, insufficient sleep increases ghrelin, the hunger hormone produced by the body. "Too much ghrelin causes your body to crave sugary and fatty foods so you can stay awake," she explains. "Leptin, which does the opposite, tells the brain when the body is full and to stop eating. Leptin plummets when you don’t get enough sleep, signaling the brain to eat more food."

Sleep is far more than just a period of rest—it’s an active and essential bodily function that can help you maintain a healthy weight, keep you safe and healthy, prevent disease and improve your day-to-day focus and performance.