A Cross-Sectional Study of Myopia and Morning Melatonin Status in Northern Irish Adolescent Children

Table 2

Relationship between age, SER, axial Length, time of saliva sample collection, bedtime, sleep latency, wake time, time asleep, global PSQI score, PAQ-C score, and morning salivary melatonin concentration.

Characteristic	Salivary melatonin
	ρ
Age	0.075	0.54
SER	0.081	0.51
Axial length	0.090	0.46
Time saliva sample collected	0.060	0.62
Bedtime	−0.008	0.95
Sleep latency	0.021	0.86
Wake time	0.046	0.70
Time asleep	0.103	0.40
Global PSQI score	−0.003	0.98
PAQ-C score	−0.105	0.39

SER = spherical equivalent refraction; PSQI = Pittsburgh Sleep Questionnaire Index; PAQ-C = Physical Activity Questionnaire for Children; ρ = Spearman’s correlation coefficient. indicates significance at  < .05.