Sleep has also been found to influence the buildup of brain amyloid, an abnormal type of protein deposit that is seen in cases of Alzheimer’s disease. In fact, lack of sleep or particularly fragmented sleep may increase the accumulation of amyloid plaques.

Scientists at Johns Hopkins University recently analyzed data from the Baltimore Longitudinal Study of 70 older adults without dementia. Subjects who reported less sleep or poorer quality sleep exhibited higher amyloid levels on their brain scans.

Other research points to the possibility that these scans also measure levels of brain inflammation, which is known to contribute to cognitive decline associated with aging. A good night’s sleep has also been shown to reduce brain inflammation.

Of course, poor sleep habits can also damage the body.

A study published in the October issue of the journal “Sleep” reported that people who did not sleep well experienced higher rates of heart disease, diabetes, and stroke.

Poor sleep quality is also linked to a larger waistline (central obesity) and elevated blood levels of appetite-stimulating hormones, which can lead to becoming overweight or obese.

The average person requires about seven to eight hours of sleep each night, but we tend to need less as we get older. However, quality of sleep matters just as much as duration. Restless sleep can leave you feeling tired the next day.

For sleep to be restorative, you need to stay asleep throughout the night. Even subtle noises that don’t actually awaken us can affect the quality of our sleep, so falling asleep with the television or radio on can lead to daytime fatigue.

Many people have busy lifestyles full of commitments, work tasks, errands, and other responsibilities that can become overwhelming and lead to stress and worry. Some have trouble “turning off ” their minds at night, making it hard to fall asleep.

Sometimes these smoldering preoccupations can awaken people in the middle of the night or extremely early in the morning. These are typical sleep patterns of people who are depressed.