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Background & objectives: Vitamin D deficiency and poor sleep quality are important factors in health disorders and are common among women. The aim of this study was to investigate the effect of physical activity on vitamin D levels and improving sleep quality in women.
Methods: This descriptive-analytical study was conducted on active and inactive women (85 individuals in each group), aged 30-48 years that were selected using convenience randomized sampling. The Pittsburgh Sleep Quality Questionnaire was used to assess sleep quality and a score higher than 5 was determined as poor sleep quality. For analysis of data, Kruskal Wallis and Mann Whitney U tests and Spearman coefficient were used at a significance level of 0.05.
Results: The results showed that 54.12% and 28.82% of women had a deficiency and insufficient levels of vitamin D, respectively, and 61.8% had poor sleep quality. Active women had higher levels of vitamin D and better sleep quality compared to inactive women (p<0.05). There was also a direct relationship between vitamin D levels and sleep quality in active and inactive women. However, this association was significant in active women with vitamin D deficiency and inactive women with different vitamin D status.
Conclusion: It seems that physical activity can increase vitamin D levels and improve sleep quality in women. But vitamin D status, especially its deficiency, may be one of the most important determinants of sleep quality in active and inactive women.

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Background & objectives: Obesity and vitamin D (VD) deficiency is associated with poor sleep quality (SQ), and lifestyle changes can effectively improve SQ. The aim of this study was to investigate the effect of high- intensity interval running training (HIIRT) with VD intake on the brain-derived neurotrophic factor (BDNF) and SQ in young women with VD deficiency.
Methods: This clinical trial study was conducted on 52 women with an average age of 25.98±1.95 years, body mass index of 27.54±1.13 kg/m2 and low VD status. After being selected by the available sampling method, the subjects were randomly divided into control, running training, VD and combined groups. HIIT performed in 12x1-min running bouts at 80-90% HRmax interspersed with one minute of active recovery. VD was consumed weekly with a dose of 50,000 units. SQ was measured using the Pittsburgh Sleep Questionnaire. Data were analyzed using one-way ANOVA with repeated measures, one-way ANOVA, Kruskal-Wallis and paired t- test (p<0.05).
Results: After 8 weeks, the levels of BDNF in the experimental groups increased and the SQ score decreased significantly (p<0.05). But the combined intervention had more effect on the change of SQ scales (p<0.05) and BDNF (p<0.001) compared to the other two interventions (p<0.05). In addition, no significant difference was observed between the changes in the SQ score of the running training and VD groups (p<0.05).
Conclusion: Lifestyle changes such as HIIT, VD intake, and combined intervention can lead to improvement of SQ through the up-regulation of BDNF in women with overweight and VD deficiency. Also combined intervention may have more potent effects on improving these variables.