The rise of modern medicine has provided a convenient altar at which the world's worriers may kneel: the health scare story.
It might not be the same as donning a hair shirt, but surely if we fret about mobile phones/x-rays/oxygen giving us cancer, take every test and gulp the right pills, a guardian angel will reward us for our vigilance with a long and fruitful life?
Not so, say Dr Susan M Love and Alice Domar, the co-authors of Live a Little! Breaking the Rules Won't Break Your Health, a new guide to healthy living published in the US late last year. In the book the pair make the case that many of us are living healthier lives than we may realise.
"We wrote the book because the media is telling us what's healthy and what's not the whole time," says Love, a clinical professor of surgery at UCLA. "People take it seriously. You must have eight hours' sleep a night, have no stress, drink eight glasses of water a day, exercise the whole time. It makes you crazy. We're simply asking what was behind these rules. Who is asking them? We wanted to find out if the old wives' tales were substantiated and most of the time they weren't."
Health experts Love and Domar tell us how to de-stress over some of the key health areas.
A survey by the US National Sleep Foundation found in 2002 that three-quarters of Americans had trouble sleeping. A third, the organisation claimed, were so sleepy during the day that their normal activities (household chores/working lives) were disrupted. But should it get our goat? The experts think such polls give off the wrong impression.
"It looks like you need at least six hours' sleep, with seven being ideal," says Love. "But if you have a lot less for a couple of days, terrible things are not going to happen. You can catch up. It's all about the general pattern over your lifetime, not what you do day-to-day.
"Unhealthy people tend to sleep a lot but if you look at the data, those who sleep for seven hours a night throughout their entire lives tend to live the longest. But if you're sleeping seven hours a night and you are still feeling exhausted you should just sleep more. There's no hard and fast rule."
We manage anxiety in the same way we would tip-toe along a tightrope. Sway too far one way, you decline into lethargy. Lean in the opposite direction and you'll land in heart-attack country. It's well publicised that worried people are courting coronaries.
According to an ongoing study in the Journal of the American College of Cardiology, of 735 American middle-aged or elderly men who had good cardiovascular health in 1986, those who scored highest on four different scales of anxiety were far more likely to suffer heart attacks in later life. What's the flip side? "No stress is not good either," says Love. "If you look at the studies, those whose heart rate never goes up are on a fast track to death. You need to have adrenaline rushes, so that when you do get stressed you know how to deal with it."
Domar agrees: "Stress improves your performance to a point, above which the way you handle things rapidly declines," she states. "You want highs and lows to live an interesting life."
Even so, there's no doubt that avoiding the upper end of the stress spectrum is probably a good idea."
Experts rally against confusion between "prevention" and "early detection".
The US National Cancer Institute recommends that women over 40 get mammograms every one to two years. Here in the Ireland, regular screening doesn't start until 50.
"Mammograms don't prevent cancer, they just catch it an early stage," says Domar.
"In the same way, a colonoscopy will not prevent you from getting polyps, it might just catch them before they become cancerous."
That doesn't mean you can skip screenings, though.
"High blood pressure, if not treated, is associated with heart attacks and stroke," Love continues. "If you detect it early you can make changes to your lifestyle that may alter it. But if you go for a mammogram that doesn't necessarily mean you're not going to get cancer. This is a common grey area."
The American Cancer Society recommends that women have their first Pap smear test about three years after they become sexually active or by age 21, whichever comes first. After that, the tests should take place every two years.
Belief that more frequent testing will make you healthier breeds false hope. "Don't get confused about it; it's the medication that will ultimately help you," says Domar.
The healthy diet rules are standard: keep your saturated fats low, avoid too much salt and sugar, maintain a balance between roughage, vegetables, fruit, proteins and carbohydrate. But be wary of rules that are too prescriptive -- five portions of fruit or vegetables a day, 2,000 calories for men and 1,500 for women, abstinence from fast food.
"The data really isn't there to support such stringency," says Love. "There's no evidence that antioxidants reduce cancer," she continues.
"We know that if you have a Mediterranean diet high in fruit, vegetables and unsaturated fats that's going to be good for you, but if you have a steak one night you're not going to drop dead."
The pair point to the lack of evidence regarding the positive effect of vitamin supplements, on which we spend millions each year in an effort to ease our health anxiety. Scientific consensus dictates that most have little or no effect, apart from vitamin D in sunshine-poor environments.
Accepted wisdom dictates that adults should get 30 minutes of moderate exercise, five days a week. "Some people can be naturally fit and they don't need to exercise so much," says Love.
"If you're a young mum and you're carting around a toddler you probably don't need to spend so much time in the gym. It can depend a lot on your age. You're going to be a lot less agile when you're older but any kind of activity is going to be useful to your wellbeing. It mirrors what happens with people's blood cholesterol. If it's naturally low you don't need to spend so long taking care of your diet."
Still, being on first-name terms with a personal trainer won't hurt.