On the basis of the findings of the univariate analysis, 12 variables were introduced for the stepwise multiple logistic regression. Table 4 shows that seven variables proved to be significant predictors of insomnia in the elderly: number of chronic diseases (OR=7.25 for having ≥5 diseases), being female (OR=2.37), anxiety (OR=1.91), watching television in bed before sleeping (OR=1.90), depression (OR=1.74), nocturia (OR=1.13), and daily sunlight exposure (OR=0.57).
The present study showed that insomnia was a common problem among the elderly with a prevalence rate of 33.4%. In South Korea, a recent study conducted by Kim et al. 14 reported a prevalence rate of 29.2% for insomnia, but when insomnia was accompanied by daytime consequences the prevalence rate dropped to 17.1%. This difference in the prevalence of insomnia may be attributed to the differences in definitions of insomnia. In Egypt, Makhlouf et al.10 in their study on insomnia among the elderly in geriatric homes found a much higher prevalence rate. Insomnia among the elderly living in geriatric homes may be associated with an unfamiliar environment, lower social support, higher prevalence of chronic illnesses, and depressive symptoms.
In the present study, aging was associated with a decreased prevalence of insomnia. Although this result was not statistically significant, it is compatible with the study carried out by Tsou 15 in Taiwan, who found that aging was associated with a decreased risk for insomnia even after controlling for covariates. Therefore, age itself may not be a contributing factor for insomnia in healthy elderly people, and the relationship between insomnia and age can be entirely explained by other factors.
Female sex is a strong risk factor for insomnia; women are more likely to experience insomnia throughout their lives, and aging increases this risk 16. Our multivariate logistic regression models confirmed this effect, with female sex being associated with an increased risk for insomnia. This sex variation may be explained by differences in domestic roles and family conflicts. Also, this difference could be due to sex differences in the prevalence of psychiatric morbidities, sociocultural factors, and coping strategies. In a systematic review by Zhang and Wing 17, women were more likely to report insomnia with a risk ratio of 1.41. The trend of female predisposition was consistent and progressive across age, with more significance in the elderly. Similarly, Xiang et al.18 and Tsou 15 found that female sex was associated with an increased risk for insomnia.
Socioeconomic condition has been linked to insomnia. In the present study, insomnia was more prevalent among those who were widowed, among housewives, among those with a low monthly income, and those living alone. However, using multivariate analyses, the present study did not identify them as independent risk factors for insomnia. In agreement with the present work, a British nationally representative survey of over 8000 persons aged 16–74 demonstrated strong links between disadvantaged socioeconomic circumstances and sleep disorders. Low household income, living in public rented housing, and not being in paid work were all independently associated with sleep disorders. Also, the divorced and widowed reported significantly more sleep disorders 19. In addition, Zhao and Hu 20 mentioned that living alone was a risk factor for insomnia in both elderly men and women.
Sleep hygiene is one of the important determinants of sleep quality in the elderly. The present study showed that the incidence of insomnia was higher among the elderly who watched TV and ate in bed before sleeping and also among the elderly who had an irregular sleep schedule. After controlling for the covariates, watching TV in bed before sleeping was significantly associated with increased risk for insomnia. In the same context, Gras et al.21 reported a higher insomnia rate among elderly individuals maintaining irregular bed hours. Yang et al.22 found significant differences between insomniacs and good sleepers as regards watching TV in bed before sleeping. However, they did not find significant differences as regards sleep scheduling.
Concerning physical activity, the present study showed significantly decreased risk for insomnia among the elderly who practiced regular physical activities. This was similar to a previous research conducted in Japan in which habitual physical activity was related to lower prevalence of insomnia among the elderly 23. Also, the present study revealed that regularly practicing hobbies was associated with a lower risk for insomnia; this was consistent with the results of a previous study conducted by Reid et al.24, which indicated that increased levels of nonphysical activities (recreational or educational activities) had positive effects on sleep quality in the elderly with chronic insomnia.
Research has explored the ability of light to strengthen circadian regulatory mechanisms and therefore enhance night-time sleep efficiency among aged persons. The current study showed that daily sunlight exposure had significantly protective effects from insomnia. Similarly, Hood et al.25 found a significant positive relationship between light and sleep quality among the elderly.
Regarding caffeinated beverage consumption, no significant association was found between its consumption and insomnia in our sample. This was totally concordant with other studies 26,27, which recorded similar findings. However, it was partially consistent with the results of Singareddy et al.28, who found that high caffeine intake was associated with the highest risk for insomnia, whereas individuals who reported moderate caffeine consumption had the lowest risk of incident insomnia. The most likely explanation is that those who avoid caffeine may be more sensitive to caffeine effects, and they have learned to avoid caffeine use.
Concerning smoking, the current work did not find any significant association between insomnia and smoking. Similarly, Haario et al.29 found matching results. In contrast, Wallander et al. 30 found a clear association of sleep disorders with smoking but in a different age group (people aged 20–79 years). However, it is possible that the effect of smoking in our analysis might be affected by the limited number of elderly who were smokers (38 persons), which limits the statistical power to identify a potential association between smoking and insomnia.
Multiple chronic diseases are associated with insomnia among the elderly 8. In the present study, prevalence of insomnia was higher among the elderly suffering from medical diseases. This was consistent with the results from thoroughly conducted epidemiological studies on sleep and medical diseases 31,32.
The present study demonstrated a range of physical symptoms that are more likely to be encountered among the insomniac elderly, such as nocturia, restless leg, bone pain, acidity, heartburn, and sleep apnea. Supporting these findings, Ohayon 33 reported that nocturnal awakening was significantly associated with chronic pain, restless leg syndrome, obstructive sleep apnea, gastroesophageal reflux, and nocturia, which was the most frequent reason for nocturnal awakenings among all age groups and significantly increased with age.
In our multiple logistic regression, nocturia was associated with increased risk for insomnia. Similarly, data from the United States National Sleep Foundation 2003 showed that more than half of the elderly perceived nocturia as the cause of disturbed sleep. This was four-fold higher than the proportion reporting pain, which was the next most common reason for sleep disturbance 34.
In the present study, the prevalence of insomnia increased with increased number of chronic diseases, suggesting an additive adverse effect of chronic diseases on insomnia. Similar findings were reported by other previous studies 32,35.
Insomnia could be a side effect of many medications used to treat some of the medical problems. In the present study, increased numbers of medications taken for chronic diseases were associated with increased risk for insomnia. Similar results were found by Tsou 15.
There is a close link between insomnia and psychiatric disorders. In our study and after controlling for confounding variables, the elderly with insomnia had significantly higher levels of depression and anxiety compared with the elderly not having insomnia. These results are not surprising considering that many previous studies found significant relationships between insomnia and psychiatric disorders 36,37.
Regarding depression, similar findings were reported in a meta-analysis by Baglioni et al.37 In addition, Fok et al. 36 concluded that depression was the strongest predictor of incidence and persistence of sleep complaints. Jaussent et al.38 reported that insomnia symptoms independently increased the risk of subsequent depression. The design used in the present study did not support the categorization of psychiatric disorders as either a risk factor or a consequence of the disorder, such as in longitudinal cohort studies. Thus, we could not determine exactly which comes first, psychiatric disorders or insomnia.
Moreover, regarding anxiety, Brenes et al. 39 found similar results to our findings. They found that elderly individuals with generalized anxiety disorder (GAD) with or without comorbid depression reported significantly higher insomnia severity, and there were no differences in sleep disturbances between older adults with GAD only and older adults with comorbid GAD and depression.
Also, the insomniac elderly had significantly higher stress scores. In the same context, Morin et al.40 found that insomniacs and good sleepers did not differ in the frequency with which they experienced daily stressors; rather it was their appraisal of those events that was different, with poor sleepers evaluating both daily minor events and major life events as more stressful than good sleepers. Moreover, Wallander et al.30 concluded that stress was most strongly associated with sleep disorders.
- The retrospective nature of the study, which was influenced by memory and selective recall biases, limit the conclusions from our data.
- Assessment of socioeconomic classes was difficult because the sample was geographically limited and under-representing of low socioeconomic classes.
- The design of the study could not categorize associated factors of chronic insomnia as either a risk factor or a consequence of the disorder, such as longitudinal cohort studies. Thus, we did not report on risk factors and consequences of chronic insomnia per se; rather we reported on associated factors.
Conclusion and recommendations
Insomnia is a common health problem among the elderly in Alexandria. In the present study, about one-third of elderly individuals suffered from insomnia. The most independent factors significantly associated with insomnia are increased number of chronic diseases, being female, anxiety, watching television in bed before sleeping, depression, nocturia, and daily sunlight exposure.
The present study examined only a limited number of potential risk factors for insomnia. It is recommended that other factors (e.g. genetic factors) should be investigated in future studies. Improving elders’ knowledge of the prevalence and risk factors of insomnia could guide the development of effective public health prevention and intervention programs for promoting better sleep quality.
The authors thank all elderly who participated in the study. The authors express their appreciation to the directors of all visited clubs for facilitating the work.
Conflicts of interest
There are no conflicts of interest.
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Keywords:© 2014 Egyptian Public Health Association
chronic diseases; elderly; insomnia; sleep hygiene