1/2-day periodicity measures the strength of day-night rhythmicity [43] and the strongest association signals (p-value < 5×10−9) were detected in the intergenic regions near UBE2F-SCLY and FBXO15 and in the intronic regions at FYB1 and CFAP44, in which intergenic regions near FBXO15 were previously found to be associated with insomnia [44] and FYB1 was associated with depression [45, 46]. This evidence concerns the gene UBE2F and major depressive disorder.