High-functioning executives are used to being successful. For most of their lives they have worked hard and reaped the dividends.
They struggle when they become overloaded – their sleep patterns are affected, they become irritable and often they don't heed the warning signs, as others would do.
There comes a tipping point when they can fall into a depression.
It is a problem in the modern world especially for those who have international jobs and work across different time zones.
The advent of Blackberrys and other mobile devices means people are constantly in contact with the office – even on holiday – which can also cause problems.
I look at it in terms of running. If your knee hurts you should rest – not run a marathon. People should think of work stress in that way too.