The Modulatory Effects of Tai Chi on the Circadian Rhythms and Sleep Quality of Seafarers in Different Navigational Regions
Abstract
The circadian rhythm and sleep quality of seafarers are critical for their health and maritime safety; however, both are highly susceptible to disruption by environmental factors specific to different navigational regions. In particular, trans-meridian (east-west) voyages involving rapid time-zone crossings, and high-latitude (north-south) voyages encountering polar day/night phenomena, can severely disrupt the human circadian system. This study aims to investigate the potential modulatory effects of Tai Chi, as a non-pharmacological and easily implementable mind-body intervention, on the circadian rhythms and sleep quality of seafarers under different navigational conditions and to explore its differential mechanisms. This paper first systematically analyzes the core challenges to circadian rhythms posed by two typical navigational regions: the former leading to phase desynchronization between the internal clock and the external environment, and the latter causing a deficiency or disturbance of the primary zeitgeber (light). Subsequently, the paper reviews the scientific evidence for Tai Chi’s role in regulating the autonomic nervous system, optimizing neuroendocrine rhythms, and improving sleep architecture. Based on this, a core theoretical model is proposed, positing that Tai Chi may act as a potent “non-photic zeitgeber”. Through regular, daily practice at a fixed time, it can provide a stable and predictable synchronizing signal to the seafarer’s internal biological clock. We further hypothesize that Tai Chi’s mechanism of action is context-dependent: during trans-meridian voyages, it primarily serves as a rhythmic anchor to accelerate phase re-entrainment and combat jet lag; during high-latitude voyages, it functions to substitute and enhance a weak or absent light signal, helping to maintain the stability of endogenous rhythms. To validate this model, a 2x2 factorial designed randomized controlled trial is proposed to prospectively compare changes in circadian rhythms (measured by actigraphy and salivary hormones) and subjective sleep quality between a Tai Chi intervention group and a control group across the two different navigational regions. This research not only aims to provide an innovative and scientific intervention for the sleep and rhythm problems faced by seafarers in extreme environments but also seeks to deepen the understanding of mind-body exercise as a form of behavioral chronotherapy, thereby opening new avenues for safeguarding the health and safety of special occupational populations.
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