Influence of patients' health beliefs on rehabilitation exercise adherence after knee replacement: the mediating role of exercise psychological needs satisfaction.

The circadian system orchestrates the 24‐h temporal organisation of physiology and behaviour and is entrained primarily by light []. In mammals, its central pacemaker is located in the suprachiasmatic nuclei (SCN) of the hypothalamus [, ]. This synchronisation depends critically on the non‐image‐forming (NIF) visual pathway, mediated by intrinsically photosensitive retinal ganglion cells (ipRGCs), which act as photoreceptors alongside rods and cones [, , ]. These phototransduction signals are essential for circadian photoentrainment [, ], pupillary light responses (PLR) [, ], light‐induced melatonin suppression [, , , ], and the regulation of sleep and peripheral temperature rhythms [, , ]. The core photopigment in ipRGCs is melanopsin, a blue light‐sensitive opsin encoded by the gene []. Because of its central role in the NIF pathway, variations in has been proposed to contribute to interindividual differences in light sensitivity and downstream circadian function [, ]. Among its variants, two missense SNPs ‐Pro10Leu (P10L, rs2675703) and Ile394Thr (I394T, rs1079610)‐ have attracted particular interest. The P10L‐T allele has been associated with chronic insomnia [], seasonal affective disorder [], and later sleep onset and chronotype [], whereas the I394T C allele has been linked to enhanced PLR [, ] and later sleep/wake timing []. However, although population studies support associations with altered NIF behaviours, the direct functional consequences of these melanopsin variants remain unclear, as and evidence has been conflicting [, ]. Assessing the influence of melanopsin variants on NIF responses in real‐life settings remains challenging because of the diversity and complexity of these outputs. Melatonin suppression may provide a useful index of melanopsin function, given their close functional and anatomical association [], and although individuals show > 50‐fold variability in light‐induced melatonin suppression [], no study had yet examined the effect of melanopsin variants on melatonin suppression and melatonin secretion under dim light conditions. Likewise, PLR represents a non‐invasive assay of melanopsin‐mediated phototransduction because it is driven predominantly by ipRGCs [], but its interpretation in daily life is complicated by the fact that light exposure varies widely in intensity, spectrum, and timing, making it difficult to isolate melanopsin‐driven responses from those of rods and cones []. In this context, circadian ambulatory monitoring of activity, peripheral temperature, and light exposure provides a valuable complementary approach for assessing daily NIF outputs under real‐world conditions [, ]. Wrist‐worn devices, in particular, offer a practical and scalable method, with advantages including low participant burden, continuous long‐term recording, high compliance [], and the ability to capture individual variability in real‐world environments across occupational, social, and seasonal contexts [, , ].