Annual variation in daily light exposure and circadian change of melatonin and cortisol concentrations at a northern latitude with large seasonal differences in photoperiod length

Table 3 Means and standard deviations for seasonal integrated exposure to illuminance and irradiance in the range 450–500 nm during the six time periods during the day

Season		Time period of the day (hh:mm–hh:mm)
		04:00–08:00	08:00–12:00	12:00–16:00	16:00–20:00	20:00–24:00	00:00–04:00
Winter	Mean (lux*min)	3499	31,829	39,325	12,227	4304	182
N = 15	SD (lux*min)	3573	12,142	16,712	5697	3335	524
Spring	Mean (lux*min)	20,848	77,887	174,058	79,184	4275	116
N = 15	SD (lux*min)	13,858	31,940	91,305	50,529	2474	176
Summer	Mean (lux*min)	71,518	172,843	371,683	726,036	52,033	88
N = 15	SD (lux*min)	38,046	95,915	252,050	344,795	69,369	119
Autumn	Mean (lux*min)	14,753	85,219	200,564	170,479	5873	277
N = 15	SD (lux*min)	8210	44,098	127,800	95,712	4141	402
Winter	Mean (μW/cm²*min)	97	3386	5238	916	267	16
N = 14	SD (μW/cm²*min)	136	3142	4777	782	719	34
Spring	Mean (μW/cm²*min)	2718	8157	14,023	5850	384	22
N = 14	SD (μW/cm²*min)	2990	5357	9833	7371	802	46
Summer	Mean (μW/cm²*min)	8503	13,762	28,070	60,170	3500	23
N = 14	SD (μW/cm²*min)	11,181	12,943	30,928	58,643	5016	37
Autumn	Mean (μW/cm²*min)	1347	7598	15,834	13,711	337	20
N = 14	SD (μW/cm²*min)	1392	5525	15,032	17,066	660	46

ISSN: 1880-6805