While on the subject of sleep, Ed Power talks to an expert on a disorder that has largely been regarded as trivial, but if ignored, can lead to severe insomnia.
Nocturia is a slightly mysterious name for a sleep disorder that affects millions. Sufferers are kept awake through the night or have their rest interrupted repeatedly. The consequences can be debilitating and sometimes dangerous, says Professor Poul Jennum, a sleep expert from the University of Copenhagen.
"When people have not slept properly they experience poor concentration. The quality of their work is impaired. Their ability to interact with others suffers. Most seriously, there is the danger of falling asleep while behind the wheel - driver fatigue is the largest single cause of road death."
Nocturia is defined as being woken by the need to go to the bathroom several times during the night. While it may sound less like a medical problem than an integral part of the human condition, in extreme cases nocturia can lead to severe insomnia, says Prof Jennum.
The most common contributing factor is an over production of urine. This is due to the body being unable to produce adequate quantities of the anti-diuretic hormone, vasopressin, which is released during sleep to ensure the volume of urine produced does not outstrip the capacity of the bladder.
"When it gets to the stage that you are getting up and going to the bathroom five or more times during the night then you can start talking about it as a disease," explains Professor Jennum, who is also head of the Sleep Laboratory at The Glostrup University Hospital, Denmark.
Nocturia disrupts our sleep by interfering with the body's diurnal rhythms. We are at our sleepiest at certain times of the night (most of us find it easiest to nod off before 1am). Once that cut-off has passed we return to alertness. The frequent need to use the toilet can carry us across the "sleep threshold" and back to full wakefulness.
Over 60 per cent of the population will experience nocturia over their lifetime. Some 30 per cent of working people will rise at least once in the night, with the rate doubling in the over 70s.
Researchers in Sweden say the productivity of a nocturia sufferer is 9.2 per cent lower than normal. This, they conclude, translates into a €3,200 productivity loss. When the cost of human discomfort is added the price becomes incalculably higher.
"Getting up in the night to pass urine can also result in falls and broken bones, particularly among the elderly," explains Prof Jennum.
The link between age and nocturia has yet to be fully explained. It has proved difficult to establish whether the ageing process is itself the trigger or if poor general health contributes (older people in good physical condition rarely complain of nocturia).
There is growing evidence that individuals who are vulnerable to other sleep disorders, such as apnea, or heart disease may be prone to nocturia. Those who wet the bed as children might be susceptible as well. Nocturia is also common in cases of Parkinson's disease.
Often the causes are more prosaic, however. People are commuting in greater numbers than ever and have started to take meals later in the evening. Drinking shortly before bedtime clearly raises the likelihood of needing to go to the bathroom during the night. Tea, for example, has a diuretic effect and is thought to be a significant contributor to nocturia, says Prof Jennum.
Nocturia has traditionally been under-reported because patients regarded is as a trivial or unavoidable consequence of growing older and were slow to tell their doctors. Such reluctance seems to be diminishing.
Prof Jennum says: "In the past 10 years or so, we have seen a far greater readiness on the part of patients who give doctors all the information and not to hold back."
No straightforward cure exists for nocturia. But the condition can be managed by making changes to one's lifestyle - for example, by drinking less before bedtime and taking more exercise. Sleeping pills should be avoided, Prof Jennum adds, as these frequently lead to dependence and in the long term could increase the risk of insomnia.
"The research would seem to suggest that the healthier you are the less likely you are to experience severe nocturia."