A bad night’s sleep can be the result of stress, poor diet, or simply not getting enough hours of rest. If you begin to fall into a pattern of back-to-back sleepless nights and find yourself experiencing daytime sleepiness, slow reflexes, and poor concentration, you may be suffering from a common sleep disorder — sleep apnea. The common yet underrecognized condition affects the way that approximately 22 million Americans breathe when they sleep at night, according to the American Sleep Apnea Association. Eighty percent of moderate and severe cases of obstructive sleep apnea (OSA) are undiagnosed, putting patients at risk for high blood pressure, chronic heart failure, and other cardiovascular problems.

The sleep disorder has also been linked to a higher prevalence of cancer mortality. In sleep apnea, there is a lack of adequate air flow traveling into the lungs through the mouth and nose, causing a reduction in oxygen levels in the blood. This common trait in sleep apnea is known to play an important role during the various stages of tumor formation and progression. In fact, the severity of the sleep disorder may predict the risk of malignant skin melanoma, according to a new study.

Findings presented at the European Respiratory Society (ERS) Annual Congress in Barcelona unveiled the link between skin cancer and sleep apnea in humans. Previous studies have examined the link between the sleep disorder and both mortality and incidence rates from cancer. However, this is the first study to analyze the relationship between a specific cancer — skin melanoma — and sleep apnea in humans. The researchers measured the aggressiveness of melanoma, along with the presence and severity of sleep apnea, in 56 patients diagnosed with malignant skin melanomas.

Sixty-one percent of patients with malignant skin melanomas had sleep apnea, while 14.3 percent had severe sleep apnea. The results of the study revealed that as the severity of sleep apnea increased, the progression of skin melanoma also increased. Extreme sleep apnea was also associated with a higher growth rate or depth of invasion of the tumor, reports Science Daily.

"This is the first study in a human sample to show that sleep apnea can worsen the outcomes of melanoma." said lead author of the study, Dr. Francisco Campos-Rodriguez, from the Hospital de Valme in Seville, Spain.

While most patients with sleep apnea suffer specifically from OSA, central sleep apnea is the second most common type of sleep apnea diagnosed. This type of sleep disorder happens when the brain doesn’t send the right signals to the muscles that are responsible for controlling breathing, according to the University of Maryland Medical Center. Some people even suffer from a combination of the two types of sleep apneas — known as complex sleep apnea.

The research findings by Campos-Rodriguez and his colleagues could have important clinical implications, if applied to a larger sample size. "If the results are confirmed in larger studies, this would have important clinical implications, particularly as sleep apnea can be easily treated and this could open up new therapeutic possibilities for people with both conditions,” Campos-Rodriguez said. The researchers have begun a bigger trial that will further analyze the link between the sleep disorder and skin melanoma, involving 450 patients with cutaneous melanoma. This study could provide a breakthrough in the treatment of skin cancer patients with sleep apnea.

According to the American Cancer Society, approximately 120,000 new cases of melanoma will be diagnosed in the United States in a year. The most preventable cause of skin melanoma is exposure to the sun.