In my experience, you can have the best diet in the world, have the best exercise program and be free from emotional stress, but if you aren't sleeping well, for whatever reason, it is virtually impossible to be healthy.

But how much sleep do you need for optimal health?

In this interview, Dr. Rubin Naimani -- a clinical psychologist, author, teacher, and the leader in integrative medicine approaches to sleep and dreams—sheds light on this question.

Dr. Naiman earned his Ph.D. in Clinical Psychology at Alliant University in San Diego.

During the 1990's, he served as the sleep and dream specialist at Canyon Ranch Health Resort in Tucson for 10 years, where he created the first formal sleep laboratory outside of a hospital setting.

Dr. Andrew Weil was also on the staff at that time. Later, he served as director of sleep programs for Miraval Resort. In previous interview, we discussed what sleep actually is, the spiritual dimensions of sleep, the primary causes of insomnia, and why sleeping pills are not the answer. Here, Dr. Naiman delves into several of the most frequently asked questions about sleep, starting with:

How Much Sleep Do You Need?

Over the years, I've come to a conclusion that there is no perfect answer to this question because like everything else, the answer depends on a large number of highly individual factors. The general consensus seems to be that most people need somewhere between six and eight hours of sleep each night.

There's compelling research indicating that sleeping less than six hours may increase your insulin resistance and risk of diabetes. And recent studies show that less than five hours of sleep at night can double your risk of being diagnosed with angina, coronary heart disease, heart attack or stroke. Interestingly enough, the same appears to be true when you sleep more than nine hours per night.

The question of the ideal amount of sleep is a topic Dr. Naiman has addressed on numerous occasions throughout his career as a sleep expert, and he agrees; people want a number, but this 'number' must be as individual as the person asking for it.

"I think asking 'how many of hours of sleep should I get?' is like asking, 'Doctor, how many calories should I eat?'" he says. "Of course the answer to that depends on who that person is. It's so individual. It also depends on the quality of those calories. Again, a lot of people are knocking themselves out night after night after night with sleeping pills. They may be getting seven to eight hours, but is it sleep? It looks like sleep. It might feel like sleep, but you know what, it's not really sleep. That's part of the question too—the quality of it."

Insufficient Sleep Puts Your Health at Risk

Dr. Naiman is familiar with the studies showing increased health risks when you sleep more or less than a certain amount, but is still cautious about taking these findings as the final word on the matter.

"There is really interesting data," he says. "I think the data is very strong showing that if you don't sleep enough, you're in trouble."