4. Discussion
insomnia, sleep disturbance, daytime dysfunction
DISORDER, CHRONIC INSOMNIA, DISEASE, CHRONIC INSOMNIA, OXIDATIVE STRESS, POSTMENOPAUSAL SYMPTOMS
The main findings of our study indicate that a one-month vitamin E prescription can improve sleep quality and reduce sedative drug use in postmenopausal women with chronic insomnia disorder. There is much evidence to back up the benefits of vitamin E in menopause, whether it is for postmenopausal symptoms or bone health [Despite these discoveries, the current knowledge about the relationship between vitamin E and sleep quality improvement is based only on descriptive data or studies in animal models. An exploratory study in 2008 by Lichstein et al. surveyed a total population of 519 men and women aged 20–98 in Shelby County, Tennessee. The study aimed to assess changes in sleep quality associated with vitamins. When separating the subgroups, the participants who were only prescribed vitamin E had better sleep quality and scores than those with no vitamin use [The PSQI questionnaire comprises seven domains: sleep quality, sleep latency, sleep duration, sleep efficiency, sleep disturbance, sleep medication use, and daytime dysfunction, in all of which the chronic stress stage is involved. Vitamin E supplementation may lower the stage of stress or resolve its chronicity through its ability to improve biomarkers of oxidative stress, described earlier in the proposed mechanism. The improvement score of the vitamin E group in this study was much greater than that of the placebo group, indicating that vitamin E improved sleep quality. When exploring micronutrient inadequacy and sleep in a large general population, Ikonte and colleagues discovered that women with adequate intakes of vitamin E below 60% were more likely to suffer from short sleep than the population as a whole [To our knowledge, the strength of this study is that it was the first randomized placebo-controlled trial to evaluate vitamin E’s effects on chronic insomnia disorder. Another strength is that our study chose the PSQI questionnaire, which is simple, internationally standardized, and validated in its Thai version for identifying poor sleepers and following up on sleep quality. The main limitation is that we did not evaluate serum vitamin E or oxidative stress markers before and after the intervention. Second, the PSQI questionnaire was designed only to evaluate sleep quality within one month, so the long-term result of a vitamin E prescription for chronic insomnia disorder is still unknown and requires further study. Third, the baseline PSQI scores in the vitamin E group were higher than the placebo group. Although we used a randomization design intending to have similar sleep quality between the two participant groups, this situation could happen by chance. While worse sleep quality in the intervention group was observed, there was more room for improvement which might raise some concern that the actual effect of vitamin E on relieving insomnia would be obscured. Nevertheless, the difference between the baseline PSQI scores of both participant groups was only two, which may not be clinically significant. Furthermore, the improvement score and rate of sedative drugs used were much better in the vitamin E group, reflecting some benefits of vitamin E supplements on sleep. Chronic insomnia disorder is a complex disease with multiple unidentified causes and various treatments available. Management options include non-pharmacological and pharmacological treatments, as mentioned in the introduction. At the same time, oxidative stress plays a role in chronic insomnia, which is improved by potent fat-soluble antioxidant supplementation, or vitamin E, as shown in our results. As a result, future research should correlate the oxidative stress level, the anti-oxidative level, the sleep disturbance, and changes in pre- and post-antioxidant, or vitamin E, supplements to further investigate this relationship.