Statistical analysis was performed using Statistical Package for Social Sciences software.



Statistical Package for Social Sciences
Genotyping of rs2305160:G>A polymorphism at NPAS2 locus was carried out by amplification refractory mutation system-polymerase chain reaction (ARMS-PCR). 
ARMS-PCR
Melatonin concentrations were determined by enzyme linked immunosorbent assay (ELISA). 
ELISA