Sleep may seem like a time for resting the body. The reality, however, is quite different. Sleep is actually a time when the body is active.

"Sleep is a basic physiological necessity," said Ives de Chazal, a physician with says Pulmonary Associates of Southern Arizona. "We heal our bodies during sleep. There are many functions that occur."

Sleep is comprised of multiple stages; each is critical, for different reasons. For example, one stage is necessary to learn and remember. Another is for the body to produce certain hormones, such as growth hormone or chemicals that help the body to heal. And all stages are important for mental and physical health.

Those functions are why skipping sleep can have negative consequences, as studies have shown. Too little sleep has been linked to poor decision making, slow response time and more risk taking. Insufficient sleep can also lead to irritability, relationship problems and behavioral disorders. Chronic sleep deficiency has been connected to depression.

Insomnia is the most prevalent sleep disorder among U.S. adults, according to the National Centers for Sleep Disorders Research. It said 10 percent to 15 percent of adults report suffering from chronic insomnia and up to 40 percent say they have some symptoms of insomnia.

Treating sleep disorders can improves a person's sense of well-being and prevent major health problems, de Chazal said.

For example, treating patients with sleep apnea "decreases significantly cardiovascular risk factors such as strokes. Patients with congestive heart failure that have sleep apnea actually improve their cardiac function and outcomes of certain diseases."

For such reasons, says de Chazal, sleep disorders should be treated.