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Wednesday, November 16, 2005
Trouble sleeping? You're not alone. An estimated 3.3 million Canadians aged 15 or older, or about one in every seven, have problems going to sleep or staying asleep, and thus are considered to have insomnia, according to a new study in the latest edition of Health Reports.
The study, based on data from the 2002 Canadian Community Health Survey (CCHS), found that just under one-fifth (18%) of these people average less than five hours of sleep a night.
In contrast, only 2% of people who did not have insomnia reported less than five hours of sleep per night.
There are no standard criteria for defining insomnia, although the most common definitions are based on frequency. For the CCHS, respondents were asked how often they had trouble going to sleep or staying asleep. Those who answered either "most of the time" or "all of the time" were considered to have insomnia.
The study echoes earlier research that found close ties between insomnia and stress, as well as chronic conditions such as arthritis that involve pain.
But it also found an association between insomnia and some less obvious factors. For example, when physical and mental health, lifestyle and socio-economic factors were taken into account, the study showed that middle-aged people (ages 45 to 64) had high odds of suffering from insomnia, as did people who were widowed and people with low education.
Weight was also a factor. High proportions of people who were obese suffered from insomnia. And the heavier they were, the more likely they were to have trouble sleeping.
The study also found that heavy weekly drinking was linked to insomnia, as was frequent use of cannabis.
Chronic pain and stress
Links between poor physical health and insomnia have been repeatedly demonstrated as many diseases involve pain or distress, or both, which can interfere with sleep.
The CCHS found that people with chronic health conditions were likely to report insomnia. For example, in 2002, more than one-fifth of people with asthma, arthritis or rheumatism, back problems or diabetes reported insomnia. Among people who did not have these conditions, only 12% did so.
Life stress was a factor in insomnia. Nearly one-quarter (23%) of people who described most of their days as being either "quite a bit" or "extremely" stressful reported insomnia. This was more than twice the proportion among people who reported little or no life stress.
At first glance, work stress also appeared to be associated with insomnia. About 17% of employed people aged 15 to 75 who said that most days at work were stressful reported insomnia. But when factors such as chronic pain, obesity, life stress and so on were taken into consideration, the relationship between insomnia and work stress disappeared.
An individual's work schedule, though, was associated with insomnia. Even accounting for chronic pain and the other factors, the odds that shift workers would report insomnia were high compared with other workers.
Connected with obesity and middle age
A link between obesity and insomnia was also found. When chronic conditions and other variables were taken into account, individuals who were extremely obese (a body mass index, or BMI, of 35 or more) had higher odds of reporting insomnia than did those of normal weight (BMI of 18.5 to 24.9). This association might be a by-product of sleep apnea, which is related to obesity and is also a risk factor for insomnia. But sleep apnea was not measured in the survey.
The prevalence of insomnia also rose with age. About 10% of people aged 15 to 24 reported insomnia. This proportion doubled to almost 20% among people aged 75 or older.
However, old age is associated with chronic conditions, and once the presence of such conditions was taken into account, seniors no longer had high odds of insomnia. In other words, the high prevalence of insomnia among seniors was largely attributable to poorer health, not advanced age.
In contrast, even allowing for the effects of the other factors, people aged 45 to 64 had significantly higher odds of reporting insomnia compared with those aged 15 to 24.
This issue of Health Reports contains four other studies.
The article "Body mass and dependency" found that obesity is associated with an individual's being dependent on others for assistance. The results suggest that in addition to its associations with pain and disease, obesity independently contributes to dependency. The relationship persisted even when other factors were taken into account, including socio-economic status, living arrangements and the level of physical activity.
For more information, contact Kathryn Wilkins (613-951-1769; Kathryn.Wilkins@statcan.gc.ca), Health Statistics Division.
"Life expectancy" analyzes reasons for the narrowing gap between male and female life expectancy. For more information, contact Marie P. Beaudet (613-951-7025; Marie.Beaudet@statcan.gc.ca), Health Statistics Division.
Diseases of the circulatory system are the major cause of illness, disability and death in Canada. The study "Diseases of the circulatory system — Hospitalization and mortality" examines recent trends in hospitalization and mortality rates because of heart attacks and stroke. For more information, contact Helen Johansen (613-722-5570; firstname.lastname@example.org), Health Statistics Division.
According to the article "Edentulism and denture use," about 9% of Canadians aged 15 or older reported to the Canadian Community Health Survey in 2003 that they had no natural teeth. This was down from 16% in 1990. The rate of edentulism among seniors aged 65 or older fell from 48% to 30% during the same period. For more information, contact Wayne J. Millar (613-951-1631; Wayne.Millar@statcan.gc.ca), Health Statistics Division.
For more information about Health Reports, contact Anik Lacroix (613-951-1807; Anik.Lacroix@statcan.gc.ca), Health Statistics Division.