'Arrogance' of ignoring need for sleep
Society has become "supremely arrogant" in ignoring the importance of sleep, leading researchers have told the BBC's Day of the Body Clock.
Scientists from Oxford, Cambridge, Harvard, Manchester and Surrey universities warn cutting sleep is leading to "serious health problems".
They say people and governments need to take the problem seriously.
Cancer, heart disease, type-2 diabetes, infections and obesity have all been linked to reduced sleep.
The body clock drives huge changes in the human body.
It alters alertness, mood, physical strength and even the risk of a heart attack in a daily rhythm.
It stems from our evolutionary past when we were active in the day and resting at night.
But scientists have warned that modern life and 24-hour society mean many people are now "living against" their body clocks with damaging consequences for health and wellbeing.
Prof Russell Foster, at the University of Oxford, said people were getting between one and two hours less sleep a night than 60 years ago.
He said: "We are the supremely arrogant species; we feel we can abandon four billion years of evolution and ignore the fact that we have evolved under a light-dark cycle.
"What we do as a species, perhaps uniquely, is override the clock. And long-term acting against the clock can lead to serious health problems."
He says this is an issue affecting the whole of society, not just shift workers.
Prof Foster said that this was an acute problem in teenagers and he had met children who sleep by popping their parent's sleeping tablets in the evening and then downing three Red Bulls in the morning.
Emerging evidence suggests modern technology is now keeping us up later into the night and cutting sleep.
"Light is the most powerful synchroniser of your internal biological clock," Prof Charles Czeisler, from Harvard University, told the BBC Day of the Body Clock.
He said energy efficient light bulbs as well as smartphones, tablets and computers had high levels of light in the blue end of the spectrum which is "right in the sweet spot" for disrupting the body clock.
"Light exposure, especially short wavelength blue-ish light in the evening, will reset our circadian rhythms to a later hour, postponing the release of the sleep-promoting hormone melatonin and making it more difficult for us to get up in the morning.
"It's a big concern that we're being exposed to much more light, sleeping less and, as a consequence, may suffer from many chronic diseases."
'Need more sleep'
Life for the Griffiths family in Rhyl, north Wales, is nothing short of hectic.
Parents Steven and Sam share the same job in the ambulance service. One works 06:30-18:30 when the other comes into work 18:30-06:30.
Throw in a 16-year-old, a 12-year-old, kickboxing classes, cycling and the fact they work in Liverpool, which is an hour away, and there's not much free time in the day.
Steven says: "In a perfect world I'd rather have more sleep, but life now doesn't let you have that much sleep.
"The kids have activities, we want to exercise and you want to cram all of that in.
"I could do with more sleep."
Pioneering genetic research is now uncovering how living life against the clock is damaging our health.
About 10% of human DNA has a 24-hour pattern of activity, which is behind all the behavioural and physiological changes in the body.
But studies have shown rhythm can be disrupted by short sleep durations or shift work.
Dr Simon Archer, who conducted the studies at the University of Surrey, said there was a "large impact" on how the body ran.
"These are all fundamental biological pathways that can be underlying links to some of the negative health outcomes that we see such as cardiovascular disease, diabetes, obesity and potentially cancer in people who don't get enough sleep or do shift work," he said.
Experiments show people can become pre-diabetic after a few weeks of shift work.
Call to action
Dr Akhilesh Reddy, from the University of Cambridge, said the body clock influences every biological process in the human body and the health consequences of living against the clock were "pretty clear cut", particularly in breast cancer.
He said: "Try to live more rhythmically, in tune with the environment and not have too much bright light before bedtime because it will affect the clock and sleep."
Prof Andrew Loudon, from the University of Manchester, said: "The problems caused by living against the body clock may be less sexy than the countless 'this or that causes cancer stories' it is none-the-less a major problem for society."
"You might not notice any short-term changes in your health following circadian disruption, but over a long period of time, the consequences could be quite severe.
"Governments need to take this seriously, starting perhaps with reviewing the health consequences of shift work, and society and legislators needs to take this on board."
Do you want to change your sleep pattern? Sleep expert Professor Russell Foster will be answering your questions from 1430 GMT . Email email@example.com