How much sleep do we really need?

[admin]

Many years ago, people routinely slept eight to nine hours a night. Things have certainly changed for engineers since then with, the internet, Blackberrys, project deadlines, a declining economy, and ever-increasing stress, there simply aren't enough hours in the day for sleep.
So, how many hours of sleep are adequate for engineers?
What do you do to stay alert and focused the entire day?

[1smartengineer]

Usually 7 hours for me and a bucket-full of coffee the next day.

[m9ro6]

Same with me: 7 hours and a lots of coffee. I don't think it's adequate, but I catch up on the weekend or go to bed earlier one night during the week.