Getting seven to eight hours a night can help you restore clarity and improve memory.

Are you tired of struggling with fuzzy thinking and a faltering memory? Tired may be the key word. "Poor sleep has an adverse impact on thinking," says sleep expert Dr. Lawrence Epstein, an instructor in medicine at Harvard Medical School. "This istrue whether it's due to a lack of sleep or a sleep disorder."

The problem

When people don't get enough sleep, their attention and concentration abilities decline. Their reaction time lengthens, they're inattentive, and they don't respond as well toenvironmental signals. That means they can't take in new information or react to dangerous situations. This is particularly worrisome if you're behind the wheel of a car. "For example, going without sleep for 48 hours impairs cognitive abilities to the samedegree as having a blood alcohol concentration of 0.1%, above the legal limit for driving in every state," 

A lack of sleep can also contribute to a long list of health problems such as heart disease, high blood pressure, diabetes, obesity, and even early death.

Causes

There are many reasons why people don't get enough sleep, chief among them not setting aside enough time. Other common causes include insomnia (difficulty falling or staying asleep); side effects from medication; sleep apnea (a type of breathing disorder during sleep); restless leg syndrome; and chronic conditions such as heartburn, heart disease, thyroid disease, depression, and narcolepsy (a disorder of sleep/wake regulation). Late-night exposure to the light from television and computer screens, as well as smart phones, can also keep us awake, stimulating our brains and making it harder to fall asleep.

Age is another culprit that affects your sleep. You'll find that the older you get, the longer it takes to fall asleep. Sleep quality also becomes poorer, resulting in dozens of awakenings during the night.