Red eyes in the morning a TV addict's health warning

Being glued to the television at night cuts into vital hours of sleep the body needs to repair itself. Photo / NZ Herald

Watching television means a third of people do not get enough sleep - in turn leading to chronic health problems, according to research.

A US study of 21,475 adults found television viewing was far and away the most dominant pre-sleep activity - accounting for almost 50 per cent of pre-bed time.

Psychiatrists were surprised to find watching television appeared to be the most important time cue for the beginning of the sleep period, rather than hours past sunset or other more biological factors.

So, in fact, television may make people stay up late, while alarm clocks make them get up early - potentially reducing sleep time below what is physiologically needed.

Sleep is important because it allows the brain to recover from the rigours of the day. Not getting enough has been found to increase the risk of obesity, heart disease and depression.

The latest study by the University of Pennsylvania, presented at the Associated Professional Sleep Societies' annual meeting in Illinois, examined the activities over-15s undertook two hours before and after bed time.

The researchers said sleeping less than seven to eight hours daily impairs alertness but despite this up to four in 10 Americans do not achieve the recommended amount.

Co-researcher Dr David Dinges said: "Given the relationship of short sleep duration to health risks, there is concern that many Americans are chronically under-sleeping due to lifestyle choices."

A further study shows people who "relax" in the evening by playing video games have trouble sleeping. The more time they spend on their favourite pastime the longer they stay awake after finally turning the computer off.

Psychologist Dr Amanda Woolems of the University of Arkansas said her findings back up a previous study that found obsessive gamers spend less time in bed, take longer to get to sleep and have shorter periods of REM sleep when we are most relaxed.

She said: "Our statistics revealed those who admitted addiction scored higher on a sleepiness scale."

Studies in children have shown that playing interactive video games can lead to significant increases in heart rate, blood pressure and respiratory rate.

The latest findings, presented at the Associated Professional Sleep Societies' annual meeting in Illinois, found addicts who play for more than seven hours a week sleep less during the weekdays and experience greater sleepiness than casual or non-gamers.

Doctors believe the bright light of a computer screen may alter the body's biological clock and suppress the natural production of melatonin, a hormone vital to the normal sleep-wake cycle.

- INDEPENDENT