Consequences of too little, too much or endless nights of broken sleep are very serious, new research has suggested.
Most experts believe that between six and eight hours is the right amount for an adult. Teenagers need about nine hours a night and young babies up to 16 hours a day.
Researchers at the University of Pennsylvania studied nearly 140,000 people and found adults on fewer than six hours a night were up to 36 per cent more likely to suffer a heart attack and 22 per cent more at risk of a stroke than those who got a good night`s rest, the Daily Express reported.
Another Japanese study found those regularly sleeping fewer than six hours a night raised their risk of a breast tumour by more than 60 per cent.
Scientists believe sleep disruption interferes with the production of a vital hormone called melatonin, which is thought to suppress the release of oestrogen, another hormone implicated in a significant proportion of breast cancers.
The link between sleep deprivation and cardiovascular disease has become more evident in recent years with studies showing five hours a night or less is linked with a higher risk of coronary heart disease.
Sleep deprivation increases blood pressure and affects hormone and blood sugar levels, which also has an impact on the heart.