Fatigue – Declining Levels of Sleep and the Effects on Health and Productivity

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It is certainly the case that in the developed world we are now sleeping considerably less than we did a generation ago. This comes as no surprise as the rise of technology means we can now entertain ourselves into the early hours.

However, the more I read the more I become convinced that a great many modern day ills could be cured if society understood the impact that not getting the correct amount of sleep has on us both in terms of performance at work (or school) and the impact on our health, especially the modern-day pandemic of obesity. It is all too easy to see sleep as a necessary sacrifice but thinking that reducing sleep will enable us to do more could not be further from the truth.

It is generally considered that we require between 7 and 8 hours of sleep a night and that getting less than six hours of sleep has negative consequences on productivity and health. It was with some concern that I came across the results of a 2006 GMTV poll that showed that 19% of us were getting the recommended 8 hours of sleep a night and that 42% of people in the South of England are getting less than 5 hours .

New parents and teenagers are typically the most sleep-deprived people in society. A study for Mother & Baby magazine of 3,000 mothers showed that mothers today average a mere 3.5 hours of sleep in the first 4 months of a child's life (versus 6 hours for their parents) and then just 5 hours after 18 months.

Another study by Actimel and Top Sante magazine in 2007 showed that 75% of women in their 30s are lucky to get 6 hours of sleep a night, 85% of 30-something women frequently feel tired and of those 59% feel tired all the time . These statistics are worrying for the health and productivity of our nation!

The US Government's National Health and Examination survey of March 2007 (18,000 people) showed that those who slept less than 6 hours a night were 23% more likely to be obese than those who slept between 7 and 9 hours. This rose to 50% for those who slept under 5 hours and 73% in those who slept under 4 hours. Boston School of Medicine also revealed that those who slept for less than 5 hours a night were 2.5x more likely to develop diabetes versus those who slept 7 to 8 hour a night.

The Harvard Business review found that a week of sleeping 4 or 5 hours a night induces performance impairment equivalent to a blood alcohol level of 0.1% (the UK drink driving limit is 0.08%). So whilst we applaud those who work long hours we would be less impressed if we saw our colleagues tucking in to a couple of pints of beer before work every day.

The problem is that fatigued people do not believe their performance is impaired even though objective scores show it is.

In respect of obesity are if we are tired we crave high-carbohydrate, sugary and fatty foods to give us a boost. We may also crave caffeine, which can turn into a vicious downward spiral as caffeine impact our ability to sleep at night – the half life of a cup of coffee can last up to 6 hours.

By not getting enough sleep we do not produce sufficient growth hormone to counter cortisol (associated with stress) which is also responsible for release of sugar into the blood stream. Excess sugar is then converted to fat and is stored around our waists.

Research conducted by Warwick and UCL (as presented last year) studied 10,308 Civil Servants between 1985 and 1988 and again in 1992. They found that the risk of dying of fatal heart disease doubles among people who cut the hours of sleep from 7 to 5 hours .

There has been some considerable research around fatigue and safety in industrial settings, particularly where shift work is involved (see Loughborough Sleep Research Centre and Surrey Sleep Research Centre here in the UK). We also understand that fatigue leads to a great many car accidents every year. Fatigue was highlighted as key reasons for other major disasters such as the Exxon Valdez, Three Mile Island, Chernobyl, Challenger Space Shuttle and the Selby rail crash. What other research has there been showing that fatigue impacts performance?

Studies at the University of Pennsylvania split 48 adults into 3 groups, each of which slept for either 4, 6 or 8 hours a night. Tasks were then undertaken to test motor skills and memory. By the 14th day the 4-hour sleepers were 14x more likely to make errors and the 6-hour sleepers 11x more likely to make errors than the 8-hour group.

This has little impact where a tired member of staff has to re-type several letters or words but it has considerably more impact where they enter the wrong numbers into a trading system (as happened in the City not so long ago) or where the work impacts people's lives.

An Occupational and Environmental Medicine Study of 1,300 doctors (in March 2007) revealed that 66% of doctors admit to having made a mistake at some point because they were tired – 40% in the last 6 months. In standard tests conducted for the experiment 1/3 were classed as sleepy – this rose to 57% in emergency medicine, 40% in anaesthetics and 38% in intensive care. Our most fatigued doctors appear to work in the most critical departments where life and death decisions need to be made regularly.

We certainly need a better level of education into sleep, sleep habits and sleep hygiene!