Lower Serum Calcium Levels Associated with Disrupted Sleep and Rest-Activity Rhythm in Shift Workers

Nutrients. 2022 Jul 22;14(15):3021. doi: 10.3390/nu14153021.


Vitamin D deficiency is prevalent in many developed countries, and several studies suggest that vitamin D plays an essential role in brain function. A recent study showed that vitamin D deficiency was closely associated with daytime sleepiness and shorter sleep time. The relationshipbetween vitamin D levels and calcium levels is well established, and calcium level regulates slow-wave sleep generation. It is conceivable that the sleep disturbance in vitamin D deficiency may be due to an altered calcium level. Nonetheless, calcium levels, sleep disturbances, and activity rhythms have not been investigated directly. Therefore, we hypothesized that calcium and vitamin D levels might be important in regulating sleep and activity rhythm, and we analyzed the correlation with calcium levels by actigraphy analysis. Interestingly, a negative correlation was found between calcium level and sleep latency, total sleep time, use of sleep medicine, and daytime dysfunction among shift workers. In contrast, non-shift workers showed a negative correlation between the calcium level and the circadian phase. These findings suggest that low serum calcium levels may disrupt sleep-wake control and rest-activity rhythm, even if they are within the normal range.

Keywords: actigraphy; calcium; non-shift worker; rest-activity rhythm; shift worker; sleep; vitamin D.

MeSH terms

  • Calcium
  • Circadian Rhythm / physiology
  • Humans
  • Sleep / physiology
  • Sleep Wake Disorders*
  • Vitamin D
  • Vitamin D Deficiency*


  • Vitamin D
  • Calcium