The following is an article from the Daily Mail, which shows us of the effects of Cortisol, also produced during stress. Cortisol is a fantastic hormone when it is produced for what its meant for and short raised bursts to deal with acute stress. However if its produced for long term stress its very detrimental on the body (see section here on STRESS AND HEALTH)

How to never get ill: Take a nap

History has many accomplished nappers.
Leonardo Da Vinci took short naps every few hours; Napoleon Bonaparte dozed on his horse. And very wise they were, too.
Lack of sleep causes the body to produce more of the hormone cortisol, which gives us energy but restricts production of human growth hormone — limiting the body’s ability to repair itself.

Sleeping baby: A report from the University of Chicago found lack of sleep can lead to heart attacks and strokes

A 2008 Stanford University study found that fruit flies’ immune systems fought invading bacteria best at night.
This backed up the theory that our bodies use dormant hours to regenerate and fight disease (by producing immune cells called monocytes).

And a recent University of Chicago report found that getting as little as an hour less sleep than needed can increase calcium levels in heart arteries by 16 per cent.
This can lead to heart attack and stroke — so catch up with a nap.

Extracted from The Secrets Of People Who Never Get Sick by Gene Stone, published by Workman at £16.99. © Gene Stone 2011.