The connection between sleep and heart disease is a two-way street: Poor sleep can contribute to heart disease, and heart disease can disturb sleep, reports the January 2007 issue of the Harvard Heart Letter.

Poor sleep has been linked with high blood pressure, atherosclerosis, heart failure, heart attack and stroke, diabetes, and obesity. The thread that ties these together may be inflammation, the body's response to injury, infection, irritation, or disease. Poor sleep increases levels of C-reactive protein and other substances that reflect active inflammation. It also revs up the body's sympathetic nervous system, which is activated by fright or stress.

Sometimes heart disease is a cause of poor sleep. People with heart failure may wake up with trouble breathing, which stems from fluid buildup in the lungs. There's also some evidence that heart failure leads to sleep apnea, a breathing problem that can awaken a person repeatedly throughout the night. Some people have nighttime angina (chest pain), bouts of atrial fibrillation, or palpitations (the sensation of a racing or pounding heart) that disturb sleep.

The Harvard Heart Letter suggests that if you aren't getting enough sleep, you may need better sleep habits like the ones listed below. If these don't work, talk with your doctor about having a sleep evaluation.

• Go to bed and get up at the same time every day.
• Use your bed only for sleeping or sex.
• If you can't sleep, get out of bed.
• Go easy on alcohol and caffeine; avoid nicotine.
• Exercise in the late afternoon.