I get used to it - I need around 7 horurs but often get only 6 or less, and I really feel it towards the end of the week.
Tired when you get up, and the rest of the day is a battle to get through.
Still lift/run though, and usually quite effectively despite lack of rest and recovery as I get used to it. Some workouts I am drained before I start but just get on with it.
There was some research on sleep published only last week, and 6hrs was seen as the critical point -
'Researchers find 'unequivocal' link between lack of sleep and increased risk of premature death' - http://www.guardian.co.uk/society/2010/ ... ture-death
'If you sleep less than six hours per night and have disturbed sleep, you stand a 48 percent greater chance of developing or dying from heart disease' - http://www.news-medical.net/news/201102 ... Study.aspxhttp://www.dailymail.co.uk/health/artic ... ttack.htmlhttp://www.telegraph.co.uk/health/healt ... early.html
However this is a more measured review of the new research - http://www.nhs.uk/news/2011/02February/ ... -risk.aspx