With the increased pace of modern life and work, bank holidays are increasingly an oasis of calm amid a maelstrom of pressure and stress. They are an ideal opportunity to catch up on sleep .
Few of us can easily tolerate sleep disturbance which persists for more than several days. Not surprisingly, sleep-related disorders are the most frequently reported health problem in the Western world, after the common cold. Up to one quarter of the adult population is affected by disturbed sleep in some shape or form.
There are a myriad causes of poor sleep. Some are unusual and relatively rare, such as narcolepsy and the sleep apnoea syndrome. Other sleep disturbance is linked to anxiety, to depression, as a side-effect of medication and to disturbances in circadian rhythms - the body's in-built, 24hour clock.
The first thing to establish when assessing a potential sleep disorder is the actual amount of sleep a person is getting. The reason for this is that our perception of how much sleep we enjoy is often an underestimate of what we're getting in reality. In addition, our sleep requirements drop sharply as we get older, which can lead to an imbalance between expectations and need. Four hours may suffice in your 80s, compared to an average seven- to eight-hour requirement for the younger adult.
A modern phenomenon, related to economic progress and success, is to cut down on sleep as a means to get more work done. Whether it is rising early to avoid the expanding rush-hour or burning the midnight oil working at home, sleep duration is under threat. This can result in sleep debt. Dr Thomas Wehr, of the US National Institute of Mental Health, has carried out research in which he allowed his subjects to sleep for up to 14 hours a night for a month. It took them three weeks to reach an equilibrium of eight hours a night - indicating a substantial sleep rebound to make up for the accumulated debt felt by their bodies, according to Wehr.
There is a well-proven correlation between sleep loss and impaired mental performance. One hour's lost sleep out of eight results in a drop of one point in the IQ scale. When accumulated over a period of time, it provides a measurable effect on short-term memory and the ability to think flexibly.
Shift work is especially bad for sleep. The majority of the nightworking population never adjusts to a shift system, especially one which is constantly changing. The evidence for this is strong. The highest number of road accidents occurs between 3 a.m. and 5 a.m. Research at Loughborough University's sleep research lab suggests that drivers who fall asleep at the wheel are responsible for one in five deaths on Britain's motorways. Many of those involved are shift workers coming home from work, when their body's natural rhythm is telling them to sleep. The Chernobyl and Three Mile Island disasters were both linked to sleep deficit - sleepy workers made bad decisions at critical moments.
At a physiological level, the explanation for this lies in the disturbance of circadian rhythm. This is our biological clock, around [circa] which the day [dies] revolves. It controls our hormones, when we sleep and also our core body temperature. It is no coincidence that the low point of this rhythm is between 4 a.m. and 6 a.m.
Shift work would not be so damaging if schedules were rotated clockwise - from days to evenings to nights. This would allow the body clock to reset itself more easily. The reason for running schedules counter-clockwise is economic, according to Prof Jim Horne of Loughborough University sleep laboratory. "If they ran the system clockwise you would get gaps, which means paying overtime".
Even for those who never work shifts, sleep can be a problem. A specialist registrar in geriatric medicine, Dr Joe Harbison, in a recent lecture at the Royal College of Physicians, pointed to the effects of medication on sleep. Even hypnotics, prescribed to help sleep disturbance, can cause a problem with day-time drowsiness. Alcohol can cause insomnia as can certain types of anti-depressants. Steroids, taken late in the day, cause alertness at night. Diuretics or water tablets may indirectly affect sleep by causing a patient to wake to pass urine during the night.
NARCOLEPSY is a rare and under-diagnosed cause of sleep disturbance. It is a lifelong disorder in which the person experiences an increase in daytime sleepiness, disturbed nocturnal sleep and episodes of cataplexy, in which an abrupt loss of muscle tone affects the body.
Dr Catherine Crowe, a sleep disorder specialist at the Mater Private Hospital in Dublin, says only 200 of an estimated 2,000 people with the disease have been diagnosed to date. "The average delay for patients attending my clinic from earliest symptom to diagnosis was 12 years for men and eight years for women. This delay can have far-reaching effects on educational attainment, career opportunities and social and family interactions," she explains.
Treatment options include a drug called modafinil (which has a 70 per cent response rate), programmed day-time naps and intensive exercise.
The Sleep Apnoea Syndrome is another relatively rare form of sleep disturbance. Apnoea means an absence of breathing and sufferers also snore excessively, so that they gasp for air with a resultant poor sleep quality. This condition is associated with an increased risk of heart attack and stroke, so again early diagnosis is important.
The main mode of treatment is continuous positive airways pressure [CPAP], using a device which keeps the air passages open and which indirectly improves sleep quality.
If you develop a problem with sleep, in most cases it will be short term and self limiting. Apply the principles of good hygiene outlined in the panel, left, and sleep will probably return to normal. If it does not, then it is important to visit your GP in order to rule out one of the rarer, but treatable, causes of sleep disturbance.
For more information on Narcolepsy, contact Sheila Farrell, Narcolepsy Support Group, 01-2895356 (evenings) or sheilafarrell@eircom.net The Sleep Apnoea Support Group is at 01-2094339
Dr Muiris Houston can be contacted at mhouston@irish-times.ie or leave messages on tel 01-6707711, ext 8511, but he regrets he cannot reply to individual medical problems.