Effects of sleep deprivation
A briefing from the Board of Science
Update 30 July 2004
Introduction
At the BMA’s 2001 Annual Representative Meeting (ARM) the following resolution on the effects of sleep deprivation was debated and passed by an overwhelming majority.
'That this conference congratulates the Board of Science for the excellent work it has produced in highlighting the risks of drug driving. It calls on the board:
(i) To commission a report into the dangers of driving when tired as many doctors do when returning home from prolonged periods of duty working for the NHS.
(ii) To investigate the effects of sleep deprivation on doctors, their well being and that of their patients.
(iii) To make recommendations in the report.'
This was discussed by the Board of Science and Education on 5 September 2002. As there is a large volume of evidence published on this topic, the Board resolved to produce a briefing detailing existing research, which will be regularly updated and to continue keeping a watching brief on all matters relating to sleep deprivation.
Sleepiness (drowsiness, somnolence, hypersomnia) is a feeling of abnormal drowsiness, often with a tendency to actually fall asleep. It is associated with memory deficit, impaired social and occupational performance, and car crashes Go to note 1. Common causes of sleepiness include short sleep time, sleep disorders and other medical conditions, such as hypothyroidism.
Tiredness (fatigue, exhaustion, lethargy) differs from sleepiness: it is a lack of energy and motivation, as well as a feeling of being sleepy. Common causes of tiredness include anaemia, use of alcohol and illegal drugs such as cocaine (especially regular use), depression, sleeping disorders and ongoing pain.
Fatigue may also accompany illnesses such as infections, diabetes, chronic liver and kidney disease, anorexia and cancer. Medications including antihistamines, anti-hypertension drugs, sleeping pills, steroids, and diuretics may all cause both sleepiness and tiredness. Go to note 2
Sleeping disorders
Sleeping disorders are disruptive patterns of sleep which may include difficulty falling or staying asleep, falling asleep at inappropriate times and abnormal behaviour whilst asleep.
Insomnia: This may be any combination of difficulty falling or staying asleep and intermittent wakefulness.
Sleep apnoea: This is repeated prolonged episodes of breathing cessation whilst sleeping. The flow of air to the lungs is restricted, and the individual may stop breathing for as long as 10 seconds. This causes snoring and laboured breathing, as well as disrupted sleep patterns Go to note 3. Alcohol appears to increase the risk of apnoea, even in those not normally affected. Sleep apnoea is associated with impaired driving performance, and greater risk of motor accidents Go to note 4.
Narcolepsy: This involves frequent episodes of uncontrollable daytime sleeping, which are usually preceded by drowsiness. The causes are unknown, although studies suggest it may be genetic. Go to note 5
Drugs and sleeplessness
The Department for Transport has identified 102 over-the-counter medicines with potential sedative actions. There are three main groups of these: antihistamines, opioids and muscarinic antagonists. Studies have found that all these medicines increase the sedative effect of alcohol, and so should not be taken with alcohol. Go to note 6
Antihistamines: Older antihistamines are known to cause drowsiness. The level and duration of this effect varies, although two (diphenhydramine and promethazine) impair performance to a greater extent than alcohol. Newer antihistamines have been developed to have a lower sedating effect. They are not entirely free of these properties, although taking them at the recommended dose is unlikely to impair performance.
Opioids: These include compounds such as codeine and morphine, and are known to cause drowsiness. Morphine is a well-known sedative, as well as a painkiller. Although codeine is labelled as causing sleepiness, studies have shown that it generally does not impair performance at the recommended dose.
Muscarinic antagonist: Only one of these compounds available over the counter, hyoscine, has been shown to cause sleepiness, and the effect is not as strong as classic antihistamines. It does however significantly reduce alertness and performance in memory tasks.
Alcohol
Alcohol can disrupt the sequence and duration of normal sleep states, as well as total length of sleep and the time taken to fall asleep. Although alcohol may reduce the time taken to fall asleep, it affects the second half of sleep: people are more likely to sleep fitfully, awaken and have difficulty returning to sleep. Even a moderate dose taken up to 6 hours before bedtime can disrupt sleep, thus causing daytime sleepiness and tiredness.
The adverse effects of sleep deprivation are enhanced by alcohol consumption. Studies involving low doses of alcohol following a disturbed night’s sleep show reduced performance on driving stimulators, even when there is no alcohol left in the blood. Therefore the problems of sleepiness resulting from shift-work may be exacerbated by alcohol consumption.
Alcoholics may experience sleep disorders as a result of their addiction, including increased time to fall asleep, awakenings and decreased quality of sleep. An abrupt reduction in heavy drinking may trigger withdrawal symptoms, including pronounced insomnia. Although this will improve as withdrawal subsides, sleep patterns may never return to normal. Resumption of drinking may apparently improve sleep (and so endanger relapse), although insomnia will return if drinking continues. Go to note 7
Shift work and circadian rhythms
Circadian rhythms are natural mental and physical changes that occur throughout the day. They are controlled by the body’s biological clock, which is affected by levels of light. Work schedules that conflict with the regulating cues, such as light, may result in sleepiness at work and sleep disorders such as insomnia.
Shift workers are more likely to suffer from physical and mental health problems. Accidents at work are more likely to occur at night, and to be of greater severity. For example, medical interns on the night shift have been found to be twice as likely to misinterpret tests as during the day. It may be possible to reduce sleepiness resulting from shift work by using bright lights, minimising shift changes and taking scheduled naps. Go to note 8
British Medical Association
'Lack of sleep needs to stop being regarded as a badge of honour and seen for the serious hazard that it actually is.' Go to note 9
In August 2000 the BMA’s Health Policy and Economic Research Unit (HPERU) undertook a review of the scientific literature on the implications for health and safety of junior doctors’ working arrangements, including the effects of resultant sleep deprivation. The review was designed to identify principles that could be applied to the organisation of junior doctors’ working patterns that would ensure protection for both the doctors themselves, and patients. Go to note 10
The resulting report, Implications for health and safety of junior doctors’ working arrangements Go to note 11, gives a detailed account of the effects of long working hours, sleep deprivation and disruption of circadian rhythms on performance and safety, health and well being, and family and social life.
The Board of Science and Education’s paper Driving under the influence of drugs: an internet resource Go to note 12, also refers to the danger of drowsiness caused by drugs such as over-the-counter medications.
The BMA’s Junior Doctors Committee (JDC) continues to push for better working conditions for junior doctors. The New Deal is a new contract for junior doctors, negotiated by the BMA and Health Departments, limiting the number of hours junior doctors should work. From 1 August 2001, it became a statutory requirement that newly qualified junior doctors work no more than 56 hours a week, or without adequate rest. The same limit was applied to all doctors from August 2003 Go to note 13. However, hospitals have been slow to implement these changes: according to Department of Health figures, between sixteen and forty percent, depending on nation, of junior doctors in the UK are working more than 56 hours a week, or without sufficient rest Go to note 14.
European Working Time Directive
From August 2004, junior doctors will be included in the European Working Time Directive (EWTD). This has applied to consultants and other career grade doctors since 1 October 1998. The timetable for implementing the Directive is outlined below.
| Date | Deadline |
| June 2000 | Timetable set to incorporate junior doctors into directive. |
| August 2004 | Interim 58 hour maximum working week. Rest and break requirements become law. |
| August 2007 | Interim 56 hour maximum working week |
| August 2009 | Deadline for 48 hour maximum working week. This may be extended by another interim of 3 years at 52 hours if exceptional circumstances apply. Go to note 15 |
The EWTD also outlines specific rest periods, including a minimum of 11 consecutive hours a day, and a minimum of 24 hours per week (which can be averaged as 48 hours over 14 days). Go to note 16
Two judgements by the European Court of Justice, SiMAP and Jaeger, have clarified the definition of working time as all time when doctors are on-call at the work place. This means that even when doctors are sleeping on-call, providing they are at work, this contributes to working time.
There is an option for individual doctors to opt out of the 48-hour week. This must be agreed with the employer in writing, and may be for a specific period, or indefinitely. The BMA has pointed out that it is important that opt-out is entirely voluntary. Pressure must not be put on employees to opt out, and it must not be a requirement of a post.
The JDC has calculated that from August 2004, the hours of junior cover lost each week as a result of the EWTD will be up to 213,000, the equivalent of 3,700 junior doctors compliant with the 58 hour week Go to note 17. This is clearly a major issue, and consideration is being given to the necessary changes to allow for implementation. The NHS Modernisation Agency (of which JDC chairman, Simon Eccles was a medical adviser) has set up a Hospital at Night project to carry out research into how to provide out-of-hours cover, and develop possible staffing models. Pilots have been run at various Hospital Trusts, and a central concept of night teams have been established. These would comprise junior doctors, consultants, nurses and other healthcare workers to cover core night work Go to note 18. Guidance has also been issued at the NHS Modernisation Agency Conference, Calling Time: Meeting the Challenge of the Working Time Directive on 18 May 2004.
The BMA and the Department of Health have produced briefings and guidance on the changes to doctors working hours. Guidance on working patterns for junior doctors is a document produced jointly with the National Assembly for Wales and the NHS Confederation, in 2002. It provides advice for ensuring implementation of the New Deal and EWTD. It focuses on meeting the targets for hours set out in the New Deal, and ensuring that the resulting new working patterns fit with the requirements of the EWTD. Go to note 19
Time is running out: the rush to reband training posts explained, May 2003 contains information on the rules and regulations regarding working hours. It covers the New Deal and the EWTD, providing guidance on what junior doctors should do as a result of these changes. Go to note 20
Time's up; A guide on the EWTD for junior doctors, August 2004 provides information on the new rules and solutions to problems resulting from the EWTD. It also offers guidance to junior doctors who have been adversley affected by the changes. Go to note 21
The Department for Transport
The Department for Transport, (DfT) has published several reports regarding sleep deprivation Go to notes 22, 23, 24, 25. The DTRL launched the Driver Tiredness campaign in March 2002. This was one year after the Selby train crash in which ten people died and more than 70 were injured when a land rover careered into the path of a passenger train, which was then hit by a freight train, near Selby, North Yorkshire. The driver of the land rover had fallen asleep at the wheel. The campaign was re-launched on 1 August 2002, and is a part of the Department’s Think! campaign Go to note 26, aiming to educate people about how they should drive safely. As of March 2002, the Highways Agency has been using their variable message signs on the motorway network to display the message ‘THINK DON’T DRIVE TIRED’ Go to note 27.
Government research shows that sleepiness accounts for 15-20 per cent of accidents on monotonous roads, especially motorways. These accidents peak around 2am-7am and 2pm-4pm, when the body’s biological clock dictates that sleepiness is higher. Men aged under 30 are more likely to be involved in a sleep related vehicle accident. It has been shown that taking a nap (of less than 15 minutes), and taking caffeine (150 mg, equivalent to two cups of coffee or two cans of energy drink) are effective in counteracting sleepiness, especially when taken together. It has been recommended that driver education and greater public awareness, as well as greater employer responsibility with regard to employees fitness to drive, are the best means of reducing sleep related accidents. Go to note 28
Other research
There is a great deal of published literature on the subject of sleep deprivation and accidents. Some examples are listed below.
Fatigue and Anaesthetists. A report from the Association of Anaesthetists of Great Britain and Ireland, looking into the effects of fatigue on anaesthetists, and consequently patients. It considers the introduction of the EWTD and reduced working hours, for trainees, and the implications this will have on quality of training. It recommends ways of reducing tiredness, providing effective rest, and protocols to ensure that adverse effects of fatigue are minimised. Go to note 29
Driver sleepiness and risk of serious injury to car occupants: population based case control study. A study in the BMJ which estimated the contribution of driver sleepiness to the cause of car crash injuries. It concluded that acute sleepiness in car drivers significantly increases the risk of a crash in which a car occupant is injured or killed. Reductions in road traffic injuries may be achieved if fewer people drive when they are sleepy or have been deprived of sleep, or drive between 2am and 5am. Go to note 30
Fatigue: time to recognise and deal with an old problem. This paper discusses the effects of sleep deprivation and tiredness on performance. It concluded that public awareness of the potential hazards of fatigue and its causes needs to be raised in general, and among drivers in particular. Employers need to understand, and take responsibility for, the impact of work-rest schedules on performance at work and on performance when driving to and from work. Lack of sleep needs to stop being regarded as a badge of honour and seen for the serious hazard that it actually is. Go to note 31
Sleep deprivation and junior doctors' performance and confidence. A study to determine whether sleep deprivation affects not only junior doctors' performance in answering medical questions but also their ability to judge their own performance. It concluded that SHOs performed better than house officers even allowing for sleep loss. Sleep deprivation had adverse effects on mood and performance but junior doctors could still monitor their performance and retain insight into their own ability when sleep deprived. Go to note 32
Fellow training, workload, fatigue and physical stress: a prospective observational study. A study into fatigue in medical trainees, looking at patient safety and the well-being of trainees, and how it limits educational opportunities of training programmes. It looked at workload, physical demand and personnel support. The study showed that fatigue adversely affects performance, increasing the likelihood of error, and so may cause patient harm. Trainees’ physical and mental health and interpersonal relations may be adversely affected, and training may be compromised. Go to note 33
Trainee fatigue: Are new limits on work hours enough? Comment on the above study. Discusses the effects of long hours and sleep deprivation on doctors and the reductions on working hours that are being introduced in Canada. It points out the need for larger studies to establish the effects of work on practitioner physiology and performance, and the safety of both doctors and patients. This would allow better monitoring of changes to working practices. Go to note 34
Sleep deprivation and fatigue in residency training: results of a national survey of first and second year residents. Survey into residents’ experiences found that over 20 per cent of residents reported sleeping an average of 5 hours or less per night, with 66 per cent averaging 6 hours or less. Those sleeping less than 5 hours were more likely to report serious accidents, conflict with other staff, working in an impaired condition and making significant medical errors. The report concluded that sleep deficit resulted from a combination of work-related, learning and personal conditions. Go to note 35
Tired surgical trainees: unfit to drive but fit to operate? Two letters highlighting the problems of sleep deprivation facing many doctors. Go to note 36
Attention and working memory in resident anaesthetists after night duty: group and individual effects. A study of response times in a variety of tasks looking at the effects of night duty. The subjects worked one night a week, and totalled an average of 60.5 hours work per week. The research showed a significant decrease in performance related to frequency of night duty and number of hours worked. Go to note 37
Age, performance and sleep deprivation. A study comparing the effects of sleep deprivation on younger (20-25 years old) and older (52-63 years old) drivers, monitoring performance, sleepiness and perception of ability. Without sleep deprivation, reaction times for older volunteers were slower than for younger ones. However, when deprived of sleep, reaction times for younger volunteers increased, whilst those for older volunteers were almost unaffected. Sleepiness and perception of performance were similarly affected for both age groups. Go to note 38
There have been many studies comparing the effects of sleep deprivation with those of alcohol consumption. Some examples are listed below.
Adaptation of performance during a week of simulated night work. A study comparing performance impairment brought about by alcohol and night shift-induced fatigue. The study showed that performance significantly decreased for both conditions. Performance impairment as a result of fatigue was never less than that induced by alcohol. Go to note 39
Impairment of driving performance caused by sleep deprivation or alcohol: a comparative study. A study comparing the effects of varying states of sleep deprivation and alcohol on simulated driving. This showed that both states showed a decline in performance, although this increased as the level of sleep deprivation increased. The sleep deprived groups were aware of reduced performance capability, whereas this was not perceived by the alcohol group. Go to note 40
Qualitative similarities in cognitive impairment associated with 24h sustained wakefulness and a blood alcohol concentration of 0.05%. A study based on previous findings of the similar detrimental effects of fatigue and alcohol on performance. It highlights the different effects of the two. Sleep deprivation slowed performance on tasks involving continuous attention, memory and learning, and accuracy on matching tasks. Alcohol had a greater effect on accuracy of tasks measuring memory and learning. In all other tasks, the two had the same effects. The study highlighted the need for the education of society into the detrimental effects of relatively short periods of sustained wakefulness. Go to note 41
Sleep Apnoea. A study by an international team of doctors has found many people with sleep apnoea do not realise they have the condition and are not receiving the treatment they need. As a result, many continue to drive even though they are up to six times more likely to be involved in a road traffic accident. Go to note 42
Sleep related organisations
Sleep Research Centre: This is a leading sleep research centre in the UK and has a worldwide reputation. The Journal of Sleep Research is one of the two international journals devoted to this issue. The Centre’s interests are broad and cover applied research (about 50%), basic research (40%) and clinical research (about 10%). Sleepiness is a common underlying theme.
British Sleep Foundation: Produces and collates information on the dangers of sleepiness and sleep disorders. These are disseminated to the public, patients and healthcare professionals through information leaflets, a website and educational events.
British Sleep Society: A professional organisation for medical, scientific and healthcare workers dealing with sleeping disorders. Promotes education and research into sleep and sleep disorders. Go to note 43
For further information please contact Nicky Jayesinghe, Senior Policy Executive, Board of Science and Education