How Sleep Affects Overall Health: A HealthCentral Explainer

When we miss a night of sleep, the toll it takes on our minds and bodies is obvious the next day. Not only do we look tired –red eyes and dark circles – but we feel fatigued and have difficulty focusing. But getting enough sleep also can provide protection against other physical and mental health issues.

Sleep apnea linked to aggressiveness of melanoma

New research presented at the European Respiratory Society Annual Congress suggests that the severity of sleep apnea can independently predict the aggressiveness of melanoma. Previous studies have looked at the connection between sleep apnea and cancer, but this is the first study in humans to link melanoma and sleep apnea.

For the study, researchers looked at 56 patients diagnosed with malignant melanoma. They measured the aggressiveness of the cancer, which included growth rate and depth of the tumor, and compared to the presence and severity of sleep apnea. They found that 60.7 percent of the patients had sleep apnea and 14.3 percent had severe sleep apnea.

Results indicated that as the severity of sleep apnea increased, so did the aggressiveness of the melanoma. Researchers say this shows that sleep apnea can worsen melanoma. A previous study in mice found that the reduced oxygen levels in the blood, which is common in sleep apnea, enhanced tumor growth.

[SLIDESHOW: 7 Tips to Prevent Melanoma and Other Skin Cancers]

Phobias fought during sleep

A recent study published in the journal Nature Neuroscience has found that emotional memory can be manipulated during sleep, which may allow for new phobia treatments that do not involve gradually introducing a person to their fear.

Researchers gave 15 healthy participants mild electric shocks while pictures of two different faces were shown to them. They also smelled different odors, such as clove, new sneakers or mint, while looking at the faces and receiving the shock. Researchers say this linked the face and smells to fear for the volunteers. Then, as the volunteers were in slow wave sleep where memory consolidation occurs, researchers released one of the odors, but this time without the faces or shocks.

When the subjects awoke they were shown the faces again. But, this time when they saw the face linked to the odor they smelled during sleep, their fear levels were lower than when they saw the other face. Fear was measured through amounts of sweat in the skin and functional magnetic resonance imaging (fMRI). The fMRI results showed that there were changes in regions linked to memory and emotions, which showed a decrease in reactivity when shown the face linked to the odor smelled in their sleep.

Researchers hope a new sleep treatment for phobias can be developed that doesn’t force a person to endure re-exposure to their fear.

Naps help preschoolers learn

Preschoolers who nap do much better on memory tests than those kids who don’t nap, according to a study published in the journal Proceedings of the National Academy of Sciences.

For the study, 40 preschoolers from six different schools were taught a visual-spatial task similar to the game Memory. They were shown pictures and asked to remember where they were located. In one instance, the children napped during the school day for an average of 77 minutes. Another time they were kept awake during that time. The kids did the memory task after either taking a nap or not, and then again the next day.

Results showed that the kids had better recall after they had napped, compared to when they didn’t. They remembered the picture location with an accuracy of 75 percent when they napped, compared to 65 percent when they stayed awake. When they napped, they performed better the next day, too. They also found that the kids who benefited most were the ones who took naps regularly, regardless of age.

[SLIDESHOW: 5 Facts on Babies and Sleep]

Lack of sleep puts black Americans at higher risk for health issues

Recent research has found that black people are more likely than whites to sleep less than seven hours a night, especially those who work in professional jobs, according to a recent study published in the American Journal of Epidemiology. The Harvard School of Public Health study found that black professionals had the highest rate of “short sleep” and white professionals had the lowest rate. Short sleep is associated with obesity, high blood pressure, diabetes, heart disease and death.

For the study, researchers analyzed eight years of data from almost 137,000 U.S. adults who participated in the National Health Interview Survey. Participants were interviewed about their health, lifestyle, jobs and socioeconomic status. After adjusting for various factors, researchers found that 37 percent of black workers were more likely to experience short sleep, compared to 28 percent of white workers.

Professional black workers were 42 percent more likely to experience short sleep, compared to 26 percent of white professionals. The only industries in which black and white workers had similar rates of short sleep were retail and food.

Researchers suggested that African-American professionals have a high work ethic that can lead to stress, disrupted sleep and other negative health effects.


Foundation, E. (2013, September 12). "Severity of sleep apnea predicts aggressiveness of melanoma." Medical News Today. Retrieved from

Ellis, M. (2013, September 24). "Fighting fears possible during sleep, study shows." Medical News Today. Retrieved from

Paddock, C. (2013, September 24). "Midday naps boost learning in preschoolers." Medical News Today. Retrieved from

Harvard School of Public Health. (2013, September 12). "Blacks in U.S. may be at higher risk for health problems from insufficient sleep." Medical News Today. Retrieved from

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The HealthCentral Editorial Team

HealthCentral's team of editors based in New York City and Arlington, VA, collaborates with patient advocates, medical professionals, and health journalists worldwide to bring you medically vetted information and personal stories from people living with chronic conditions to help you navigate the best path forward with your health—no matter your starting point.