JMIR Publications

ABSTRACT

Background:

Insomnia, the most prevalent sleep disorder, is characterized by dissatisfaction with both the quantity and quality of sleep. Individuals suffering from insomnia commonly have problems such as initiating and maintaining sleep, frequent awakenings, and early-morning awakening with an inability to return to sleep, which result in daytime dysfunction1,2. This condition is associated with negative long-term health outcomes, including decrease of quality of life and increase the risk of chronic diseases such as heart diseases, musculoskeletal problems, diabetes, and cognitive decline, as well as increase the risks of physical and psychological morbidity. Additionally, sleep deprivation may result in altered immune function 3–7. The prevalence of insomnia varies around the world, ranging from 10% to 60%, depending on the disease status and mortality8–10. In Malaysia, the prevalence of insomnia is also notable. A community-based survey in four urban regions in Malaysia revealed that 33.8% of adults reported insomnia symptoms, with 12.2% suffering from chronic insomnia11. Aside from that, numerous research that investigated the relationship between gender and insomnia symptoms reported that women are more likely to have insomnia symptoms than males12–14. Insomnia has a multifaceted aetiology that includes biological, psychological, and environmental factors. In addition to its established role in bone health, emerging evidence suggests that vitamin D plays a crucial role in various physiological functions, including those related to sleep regulation and circadian rhythm. Vitamin D is suggested to have a significant role in serotonin and melatonin regulation, emphasising its relevance to sleep regulation15. A meta-analysis of … studies/populations supports the association between vitamin D deficiency (VDD, serum level of 25(OH)D <20 ng/mL) and an elevated risk of sleep disorders (OR: 1.50, 95% CI: 1.31, 1.72)16. Furthermore, research indicates that women are more susceptible to insomnia due to vitamin D deficiency. A study involving 459 women revealed a significant relationship between the circadian rhythm of sleep and dietary vitamin D intake, suggesting that later sleep acrophase, the time at which the peak of rhythm occurs, was associated with higher dietary vitamin D intake17. Despite extensive sun exposure throughout the year in Malaysia, certain populations, particularly women, exhibit a relatively high prevalence of VDD due to indoor activities and their clothing behaviours. Moreover, some natural sources that contain moderate to high amounts of vitamin D, like oily fish, fish liver oil, and wild mushrooms, are not commonly available and consumed in low- and middle-income countries, contributing to this inadequacy18. Previous Research on Vitamin D supplementation for insomnia The effect of vitamin D supplementation on the sleep quality was investigated in a previous study of individuals aged 20-50 with sleep disorder. After controlling for confounding variables, the intervention group (receiving 50,000 IU vitamin D3/week) demonstrated significantly reduced Pittsburgh Sleep Quality Index (PSQI) mean scores compared to the placebo group (p<0.05), indicating improved sleep quality19. However, conflicting results reported in other studies. Mason et al. (2016) reported that 2000 IU/day vitamin D supplementation resulted poorer sleep quality in overweight postmenopausal women with low serum 25(OH)D levels. Women receiving vitamin D showed no significant changes in quality of life (p>0.05) and overall sleep quality (p=0.21) compared to the placebo 20. Notably, these studies lacked objectives sleep measures for comparison with subjective sleep outcome. Subjective measures can be biased, whereas objective measures provide more accurate data Given the conflicting findings across studies, the inclusion of objective sleep assessments could have helped clarify whether observed changes were real or marely perceived. Research on the effect of vitamin D3 on insomnia is still scarce, especially in Asian populations. To the best of our knowledge, there were no studies that have been conducted to investigate the efficacy of vitamin D3 50,000IU as a treatment of insomnia symptoms in the Malaysian population.

Objective:

This study aims to investigate the effectiveness of vitamin D3 (50,000IU) supplementation in improving insomnia symptoms in woman with VDD. The insomnia-related outcomes measured in this study are: 1) subjective sleep quality, 2) insomnia severity index, 3) daytime sleepiness, 4) sleep efficacy. Other than that, this study also aims to investigate the expected secondary outcome of Vitamin D3 supplementation to improve functional outcomes of daily activities and quality of life in insomnia woman with low serum vitamin D level.

Methods:

Trial design This study is a double-blind, randomised, placebo-controlled trial. It employs one intervention group and one control group, designed in a parallel group. This superiority trial aims to demonstrate that the response to the investigational product (vitamin D3) is superior to that of a placebo. Research Participants The study participants are women who are eligible and willing to participate in the study and are currently residing in Ipoh, Perak, Malaysia. The participants must fulfil all the inclusion criteria which are: 1) Woman, aged 19-50 years old, 2) Serum 25(OH)D level of <20 ng/mL (50 nmol/L), 3) PSQI score of ≥5, 4) Not pregnant or lactating, 5) Not sleeping with infant (< 2 years), 6) Currently (consider from the past 3 months) is not taking vitamin D or any supplements containing vitamin D, 7) Not a smoker and/or alcoholic. Participants will be excluded based on whether they have the following causes or risk factors that may contribute to insomnia: 1) Currently having the significant health problems (Malabsorption; chronic diseases such as diabetes, hypertension, cardiovascular disease; osteoporosis or other bones diseases; malignancy; hypo-or hyperthyroidism; and psychological-related illness, such as depression and anxiety), 2) Taking medication regularly (included corticosteroids, anticonvulsant, antihistamines, cytotoxic agents, Antiretroviral drugs, narcotics and psychotropics, such as antidepressant and antipsychotics). Sampling Method and Recruitment Sample Size Calculation The sample size is determined using the formula for parallel randomized controlled trial with superiority trial design, where the measured outcome type is continuous. To ease the calculation, the sample size calculator is utilised21. The sample size is calculated based on the following parameters: A significance level (or type I error rate, a) is 5% (0.05) The power (b) is 80% (0.8) The sample size ratio of treatment to control (k) is 1:1 The true allowable difference in mean of study parameter (Sleep quality score) between groups from previous studies is assumed as d= 1.92≈2 19 The SD from previous studies is assumed to be 3.1419 The superiority margin (clinically meaningful difference) is 20% (i.e., δ=0.2) The dropout rate is assumed as 10%22 Each treatment and placebo group consists of 42 participants, hence the total sample size for this study is 84 participants. Sampling and Recruitment Process The recruitment and study period take place from January to December 2025. A convenient recruitment method is employed to recruit participants from the community. The initial outreach includes disseminating the advertisements for participant recruitment via the media like posters and leaflets. The advertisements will be distributed in public areas such as community centres, pharmacies, educational institutions, and on social media platforms. It contains information regarding the study, eligibility for participant as well as the benefits that will be provided (which are vitamin D level measurement and tokens of appreciation for joining the study). Prospective participants will reach out to the researchers using the provided contact details in the advertisements. The investigator will arrange an appointment with the potential participant for the initial screening process and explain the nature of the study. Informed consent will be obtained from eligible participants, emphasizing the voluntary nature of participation, the right to withdraw at any time, and the assurance of confidentiality. Participants will receive both verbal and written information about the study. The information sheet contains details that will help them understand the study. At the end of the study, participants will receive a token of appreciation in the form of cash. They must also sign a consent form to indicate their willingness to participate in the study before enrolment. Screening Prior to Enrolment A series of evaluations and tests will be conducted to determine the participants' eligibility for the study. This data also will be included as baseline data of participants. The screening process will include: Evaluation of participants' characteristics based on the inclusion and exclusion criteria. Assessment of insomnia symptoms using validated questionnaires (Insomnia Severity Index (ISI) and PSQI) Measurement of serum 25(OH)D level in the blood. The participants must have low baseline of serum 25(OH)D level (<20 ng/L). Those who meet all the criteria will be enrolled in the study. Blinding and Randomisation Study participants will be randomised into two study groups: the placebo group (PG) and intervention group (IG). A double-blinding method will be applied for both subjects and investigators. The placebo and intervention group will be labelled as either group A or B. A third party (an appointed pharmacist) will draw lots using a coin to determine which group will belong to IG or PG. The result will be enclosed in a sealed envelope and stored by the third party in a locked cabinet. The envelope will be kept secure by the third party and researchers will not have access to it. The identity of the intervention group, either participants in group A or B, will be disclosed upon completion of the data analysis. The block randomisation method will be employed to assign participants to one of the groups. This method is preferred due to slow recruitment and to ensure a balanced number of participants are assigned to each group. A block size of four was selected because there are two intervention types (placebo and vitamin D). Given a total of 84 subjects for PG and IG, and a block size of 4 (four), 21 blocks are required. There are 6 (six) possible permutations that allow two As and two Bs in each box (AABB, ABAB, ABBA, BAAB, BABA and BBAA). The randomization code for blocks can be generated by producing a random-number list for permutations 1-20 using the block randomization generator, Sealed Envelope Ltd. 202223. Study flow Figure 1 displays the details of study flow. Baseline parameters will be taken at recruitment and randomised assigned into two arms. Outcome assessment will conducted at week-0, week-5 and week-9. Participants will be instructed to maintain their normal levels of physical activity, eat their regular meals or not to change their diet, refrain from taking any additional dietary supplements, and refrain from attempting to lose weight during the study period. Pre-intervention assessment (Week 0) Following randomisation, participants will complete pre-intervention assessment involving subjective measurements using structured questionnaires (ESS and FOSQ-10) and objective measurements of sleeping parameters using an Actigraph for one week every sleep time (only during the first week/Week 0). The data will serve as baseline information for the study participants, in addition to the data collected during the screening before enrolment (Vitamin D level, ISI score and PSQI score). Intervention (Week 1-9) Participants in intervention group will be instructed to consume 50,000 IU of vitamin D3 capsules, one capsule per week), over 9 weeks, whereas those in the placebo group will take the placebo capsule, one capsule per week, for the same duration. Subjects will be instructed to take the product once weekly with food in the morning or after breakfast. Participants will be asked to report any drug use and any changes in their health condition that occur throughout the trial period. Follow up (Week 5) At week-5 of the study, the follow up on patients outcome will be done by subjective measurement using PSQI, ISI, ESS, and FOSQ-10. The researcher will also evaluate adherence to the schedule using the pill counting method. Post intervention assessment (end of week 9) Post intervention outcome assessments will be conducted in week 9, involving 7 days (one week) of actigraphy measurement, and the collection of questionnaire scores at the end of the study (PSQI, ISI, ESS and FOSQ-10 score). Vitamin D level test will be also carried out at the end of week 9. Data analysis then will be carried out to obtain the study results. Strategies to ensure the adherence to the intervention The researcher will actively contact participants via message or phone call to remind them of their vitamin D/placebo intake and ensure they take the dose every week. A recurring weekly reminder will also be set on the participants’ phones, scheduled for the same morning each week over a 9-week period. Participants who miss a dose for one week or cannot be reached for follow-up will be withdrawn from the study. Figure 1. Flow Diagram: study design and data collection procedures. PSQI: Pittsburgh Sleep Quality Index; ISI: Insomnia Severity Index; ESS: Epworth sleepiness Scale; FSOQ-10: Functional Outcomes of Sleep Questionnaire-10 Outcomes Evaluation Table 1 presents a detail overview of the assessments employed in this study. Outcomes measure in this study include: Outcome 1: Vitamin D level status Method: Biochemistry test, utilising a Chemiluminescent Microparticle Immunoassay (CMIA) method The blood test will be performed at BP Specialist Centre located in Ipoh, Perak, Malaysia. The blood sample will be collected in the early morning after 8-hours overnight fast, at the beginning of enrolment (week 0) and at the end of the study (week 9). Only participant with serum 25(OH)D levels <20ng/L will be included in this study. Outcome 2: Changes in sleepiness severity Assessment tool: Insomnia Severity Index (ISI) questionnaire ISI validated questionnaire is a short subjective instrument used to assess the insomnia symptoms and their consequences. It comprises 7-items that assess sleep initiation, sleep maintenance, early morning awakening, influence daily activities, perceived importance of worsening influenced due to sleep disorders, concerns about sleep problems, and contentment with sleep patterns. The severity of each item is graded on a scale of 0 to 4. The sum of the seven ratings yields a total score ranging from 0 to 28. The scoring system for insomnia is as follows: a score of 0–7 indicates no clinically significant insomnia, 8–14 means subthreshold insomnia, 15–21 indicates clinical insomnia (moderate severity), and 22–28 means clinical insomnia (severe)”. A decrease in total score indicates improvement. Outcome 3: Sleep Quality Assessment tool: Pittsburgh Sleep Quality Index (PSQI) questionnaire. The PSQI contains 19-items that are used to assess seven domains of sleep quality: subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, daytime dysfunction, sleep disturbance and use of sleeping medications. Four of the items allow respondents to provide their own answers, including their usual bed and wake times, the number of minutes it takes them to fall asleep, and the number of hours they sleep per night. The remaining items require responses on a 4-point Likert scale, with higher scores indicating poorer sleep quality. Five additional items are completed by a bedpartner but are not included in the calculation of the global sleep quality score (range = 0–21). The sum of the seven domain scores yields a global sleep quality score. A total PSQI score of greater than 5 indicates a “poor” sleeper, with the higher scores indicating worse sleep quality. Outcome 4: Subjective daytime sleepiness Assessment tool: The Epworth Sleepiness Scale (ESS) questionnaire Participants' subjective daytime sleepiness will be assessed using the Epworth Sleepiness Scale (ESS) questionnaire. The ESS uses a 4-point Likert response format to measure the likelihood of dozing in various common situations. Each item is rated on a scale of 0 to 3, with higher scores indicating more severe sleepiness. Item responses result in total scores ranging from 0 to 25. A total score of 10 or higher indicates excessive daytime sleepiness. Outcome 5: Daytime function Assessment tool: Functional Outcomes of Sleep Questionnaire (FOSQ-10) The FOSQ-10 will be used to evaluate the impact of excessive sleepiness disorders on functional outcomes of daily activities and sleep-related quality of life. It focuses on five domains: general productivity, activity level, vigilance, social outcomes, and intimacy and sexual relationships. The FOSQ-10 consists of 10 questions about difficulty performing daily tasks due to sleepiness, which are rated on a 4-point Likert scale. Respondents may also indicate that they do not engage in the activity due to reasons other than sleepiness or tiredness. A higher total score indicates a better functional status. Outcome 6: Sleep parameters assessment Tool: ActTrust2 As an objective sleep measurement tool, an actigraphy method will be used to determine some sleep parameters such as sleep pattern and sleep efficiency over a one-week period at the beginning and the end of study. The actigraph used in this study is ActTrust-2 by Condor instrument Co.Ltd Table 1 Summary of measurements Measurements Instruments Timeframe T0a T1b T2c T3d Sociodemographic and lifestyle Questionnaire x Serum 25(OH)D level Biochemistry test (CMIA) x x Sleep quality PSQI x x x Sleepiness severity ISI x x x Subjective daytime sleepiness ESS x x x Daytime function FOSQ-10 x x x Sleep parameter assessment Actigraph x x aScreening phase bWeek-0: Baseline assessment cWeek-4: Follow-up assessment d Week-9: End of study week PSQI: Pittsburgh Sleep Quality Index; ISI: Insomnia Severity Index; ESS: Epworth sleepiness Scale; FSOQ-10: Functional Outcomes of Sleep Questionnaire-10 Safety measures Adverse events associated with vitamin D3 supplementation will be monitored throughout the study. Participants will be instructed to report any symptoms or adverse events that occur during the study. If experience any adverse event(s), they will be referred to the general practitioners (GPs) and blood samples will be collected to assess some parameters that can indicate the need for study discontinuation. These parameters include a serum 25(OH)D level higher than 150 ng/mL (375nmol/l), a serum calcium level higher than 10.3 mg/dL, hypercalciuria and the glomerular filtration rate that lesser than 50 mL/min/1.73 m2 (Marcinowska-suchowierska, 2018). The participant will receive the necessary treatment accordingly. Statistical Analysis The SPSS Statistic for Windows program (version 23 IBM Corp) will be used to analyse all data. Prior to selecting the appropriate SPSS test for analysis, the data will be assessed for normality and homogeneity. Normality will be examined using the Kolmogorov–Smirnov test and Q-Q plot. Descriptive statistics will be applied to analyse categorical variables, such as data from participant characteristics. Quantitative data from descriptive statistics will be expressed as mean ± SD, while qualitative data will be presented as numbers and percentages. A p-value of < .05 will be considered as significant. 1. Comparison between the characteristics of the participant in intervention group and placebo group will be examined using two-tailed, independent sample t-test. 2. Comparison between the outcomes from before and after intervention within group will be examined using two-tailed, paired sample t-tests or Mann–Whitney U test, or the Chi-square test as appropriate. 3. Comparison of the post-intervention outcomes between A and B will be examined using two-tailed, independent sample t-tests. 4. Covariance analysis (ANCOVA) will be used to examine intervening variables from demographic variables.

Results:

Vitamin D3 deficiency (VDD) is prevalent among individuals seeking sleep medication for insomnia. It may be a contributing factor to common symptoms of sleep disorders including chronic nonspecific pain, poor sleep quality and impaired experience of wakefulness22. Various studies have suggested that changes in vitamin D metabolism play an important role in the presentation and severity of sleep disorders. It is independently associated (OR=0.84) with sleep maintenance difficulties17. A study by Zhao et. al. (2017) proposed that measuring serum 25(OH)D level is probably useful in judging pharmacotherapy treatment outcomes in individuals with chronic insomnia. A serum 25(OH)D concentration <20 ng/ml in individual with chronic insomnia was independently associated with a higher probability of treatment non-response at 2 months (OR 11.636, CI 95%, P<0.001)23. Another study involving 940 healthy adolescent girls who received 9 weeks of vitamin D3 supplementation (50000 IU vitamin D3/week) demonstrated a significant improvement in cognitive abilities (P<0.001) and a decrease in the occurrence of insomnia and daytime sleepiness. The prevalence of insomnia reduced from 15.0% to 11.3% and sleepiness reduced from 15.6% to 14.7 %. Cases with both insomnia and sleepiness were reduced from 8.0% to 6.1%; P<0.0521. On the other hand, a study failed to demonstrate any significant effect of vitamin D supplementation on various sleep outcomes in vitamin D-deficient population. Among the 189 participants in the study, 92 received a bolus dosage of vitamin D 100,000 IU (2500 mg), followed by a weekly dose of 20,000 IU (500 mg), whereas 97 were given a placebo. The result showed that vitamin D supplementation did not have a significant effect on mean sleep duration, mean daytime sleepiness score, or recovery from inadequate sleep duration, excessive daytime sleepiness, or insomnia after four months of treatment 24. Other than that, Mason et al. (2016) found that overweight postmenopausal women with low serum 25(OH)D levels had poorer sleep quality following 2000 IU/day vitamin D supplementation. Compared to the placebo, vitamin D did not improve quality of life (p>0.05) or sleep (p=0.21) in women 20. The inconsistent findings from previous research underscore the need for more randomised controlled trials with specific parameters to support the benefit of supplementing vitamin D3 in individuals with insomnia symptoms. This study protocol outlines the design and rationale for a randomized controlled trial, investigating the potential benefits of Vitamin D3 supplementation in improving insomnia symptoms among Vitamin D-deficient Malaysian women. The study design holds promise for addressing the underexplored association between Vitamin D status and sleep quality within this specific population. The decision to focus on Vitamin D-deficient Malaysian women is strategic, given the higher prevalence of Vitamin D deficiency and insomnia in this population. The study aims to provide insights into whether addressing Vitamin D deficiency through supplementation can lead to improvements in insomnia symptoms, a significant concern for women's health and well-being. This proposed trial introduces a placebo-controlled design, which enhances the ability to distinguish the particular effects of Vitamin D supplementation on insomnia symptoms. Incorporating subjective and objective measurements, such as validated sleep assessment tools and self-reported sleep quality, strengthens the comprehensiveness of the study, capturing both objective and subjective dimensions of sleep. The findings of this randomized controlled trial have the potential to contribute valuable evidence to the growing body of literature on the relationship of Vitamin D status and sleep quality as well as the benefit of vitamin D3 supplementation for individual with insomnia symptoms. Successful implementation of the study protocol may inform future interventions aimed at improving sleep outcomes in populations with Vitamin D deficiency. Additionally, the findings may pave the path for targeted therapies addressing both Vitamin D deficiency and sleep problems in this specific population. Limitations While the study's design is solid, several considerations merit attention. The relatively short duration of the intervention raises concerns about the sustainability of any observed improvements and the potential long-term effects of Vitamin D3 supplementation on sleep. Its focus on a specific demographic group may limit the generalisability of the findings. Additionally, the study did not investigate potential underlying mechanisms by which Vitamin D3 may impact sleep, warranting further investigation. Nevertheless, the trial may serve as a foundation for future research investigating the long-term impacts of Vitamin D3 supplementation on sleep outcomes. Comparison with Prior Randomised Controlled Trial To the best of our knowledge, this study is the first to investigate the use of vitamin D3 supplement to alleviate insomnia problem that represents Southeast Asia population, particularly in Malaysia. Previous studies on this topic were predominantly conducted in Iran, with a few conducted in the United States of America (USA) and Ireland20,25,26. We anticipate that the findings from our study will contribute significantly to the existing knowledge on this topic and serve as a reference for Asian countries. This study specifically targets women aged 19 to 60 years. A similar study that also measured sleep quality exclusively focused on women, particularly overweight post-menopausal women20. In our study, menopausal women will also be included; however, due to the inclusion of a younger age range, the results are expected to be more conclusive. Another study included a similar age range (20-70 years) but focused on women with fibromyalgia, while our study solely involved healthy individuals with insomnia problem27. A study by Ghaderi et. al. included participants of both genders within a similar age range (from 25 to 71 years). They administered a high dose of Vitamin D3 (50,000 IU) every two weeks for 12 weeks. Similarly, our study also used 50,000 IU Vitamin D3, but it was given weekly for 9 weeks. This difference stems from our focus on participants with Vitamin D deficiency (VDD), as previous studies have shown that high-dose Vitamin D3 supplementation significantly increases vitamin D levels when given for at least 8 weeks. By providing Vitamin D3 every week for 9 weeks, we aim to help participants achieve sufficient levels. Other than that, their study primarily focused on vitamin D supplementation's impact on psychological symptoms and metabolic profiles in maintenance methadone treatment (MMT) patients. Sleep quality was assessed using the PSQI as part of their evaluation of patients' physiological symptoms28. Regarding study participants, our study will exclusively include healthy individuals with insomnia problem without chronic diseases or comorbidities. This approach minimises potential confounding factors that could impact the investigation's outcomes. Some previous RCTs included patients undergoing methadone treatment, suffering from chronic lower back pain (LBP), fibromyalgia syndrome, obstructive sleep apnoea (OSA), and depression26,27,29–31. We observed two RCTs that also only involved healthy subjects, but one used a different intervention by providing Vitamin D3-fortified milk or yogurt32. Another RCT, which shares more similarities with ours, only measured sleep parameters subjectively using the Pittsburgh Sleep Questionnaire index (PSQI). It measured seven parameters, including sleep duration, sleep latency, sleep efficiency (equivalent to actual sleep duration from the entire time spent in bed), sleep disturbance, use of sleep medications, and daytime dysfunction19. In terms of the outcomes evaluated and assessment method, our study comprehensively evaluates insomnia-related outcomes objectively and subjectively. However, our study not only incorporates PSQI for subjective outcome measurements but also includes the Insomnia Severity Index (ISI) to measure insomnia severity, the Epworth Sleepiness Scale (ESS) to assess daily sleepiness, and the Functional Outcomes of Sleep Questionnaire (FSQI) to gauge participants' quality of life related to insomnia. A notable strength of our study lies in incorporating objective measurements of sleep parameters using Actigraphy technology (ActiTrust-2 from Condor Ins.). The Actitrust-2 provides objective measurement outcomes such as sleep efficiency, sleep latency, total sleep time, time in bed, and wake after sleep onset (WASO). This addition enhances the accuracy of our study's objective results from participants.

Conclusions:

This current study builds upon previous research that has demonstrated the positive effects of vitamin D supplementation on insomnia symptoms. However, it focuses on a different population and measures more insomnia-related outcomes subjectively and objectively in order to provide more reliable findings. Ultimately, this randomized controlled trial will contribute valuable evidence supporting the potential benefits of Vitamin D supplementation in improving insomnia symptoms among individuals with VDD, especially Malaysian women. The findings will emphasise the importance of considering Vitamin D status in the management of sleep disturbances and advocate for further research to optimise interventions for diverse populations. Clinical Trial: ISRCTN69678101