I have always heard that 'hard work never killed anyone'. I know very high energy people who can not sleep beyond five hours a night. A lot of them are my contemporaries, in their sixties and seventies and doing well physically.

I suspect the lack of sleep for the person mentioned here is probably due to his physiology interacting badly with his personality - he seems to be an 'A' type personality. I am sure his body was giving out warning signs, that he probably dismissed or missed.

I do not think that there is a prescribed amount of sleep necessary for everyone. It can vary from as little as 4 hours to all the way to 9 hours, depending on one's physiology. I think the factor that kills is tension that causes hyper tension and if your genes are susceptible to heart attack, then you are at very high risk.

Learn to listen to your body's cries for help, as it always tries to warn you beforehand.

Regards,
KRS