In one study, 15 percent of Americans reported suffering from chronic pain, and two-thirds also reported having sleep problems. Back pain, headaches, and temporomandibular joint syndrome (problems with the jaw muscles) are the main causes of pain-related sleep loss. More from Health.com: 7 Steps to the Best Sleep Ever
Mental Illness and Stress
Insomnia is both a symptom and a cause of depression and anxiety. Since the brain uses the same neurotransmitters for sleep and mood, it's often hard to know which starts first.
Stressful situations or events, such as money or marital problems, often kick off insomnia that can become a long-term problem.
If you are one of the 37 million chronic snorers in the U.S., your buzz saw may be no big deal; an estimated 30 to 50 percent of Americans snore, most without consequence. But in some cases snoring is a symptom of sleep apnea, a disorder linked to heart disease, high blood pressure, and stroke.
Crossing over time zones throws off your internal clock, which tells your brain to sleep when it's dark and wake up when it's light. Your body can take up to three days to adjust to the new light/dark schedule in another time zone, and if you fly across time zones often, jet lag can cause chronic sleep problems.
A schedule that's contrary to normal wake-sleep hours - like those of doctors, nurses, or other shift workers - can upset your body's circadian rhythm.
People who work rotating shifts have lower levels of serotonin, a hormone and neurotransmitter in the central nervous system that helps regulate sleep, according to a 2007 study at the Universidad de Buenos Aires, in Argentina.
Often, sleep difficulties surface along with other medical conditions. With lung disease or asthma, for example, wheezing and shortness of breath can disrupt your sleep, particularly in the early morning. If you suffer from heart failure you may develop abnormal breathing patterns. Parkinson's and other neurological diseases count insomnia as a frequent side effect.