How much sleep do you really need?

In answer to the above question, probably more than I've had over the past three days trying to transport a tired and teething 16-month old from London to Wellington, here in New Zealand. However, several research studies seem to triangulate upon the finding that 6.5 to 7.5 hours seems like the magic window. Most interestingly, mortality risk seems to go up for those people who regularly sleep more than 7.5 hours a night - and is of more concern than those who sleep, say under 7 hours a night. This finding seems to be replicated using different methodologies and studying different population groups, suggesting that this appears to be reliable. However, a lot of these earlier research studies relied upon self-reported sleep. More recent studies have used wrist monitors to better measure actual sleep - though it isn't fail proof. Using this method, it looks like women who slept less than 5 hours a night, or more than 6.5 hours were less likely to be alive 14 years after the study ended.

So, thinking of cutting back on your sleep. Wait a minute. There is also evidence to show that cutting back too much on your sleep has an impact on your fat loss potential. Losing sleep boosted production of a hormone called ghrelin, which has been implicated in interfering with fat-burning processes and can stimulate hunger pangs. Sleep deprivation is known to raise blood pressure and reduce glucose tolerance, which can both increase the risk of artery damage.

So, how much sleep do you need? Depends what you are trying to do - but I try not to sleep more than 7-8 hours a night, and have to try to get more than 5 if I can (travel schedule and crying baby allowing). And with that, I am heading off home for an early night.

How much sleep do you believe you need?