Table 4 Means and standard deviations for seasonal and annual mean melatonin concentration at the six time points during the day

Winter

Mean (pg/ml)

3.12

2.30

1.94

4.52

6.74

3.82

SD (pg/ml)

4.59

2.51

1.47

2.95

5.15

1.91

Spring

Mean (pg/ml)

2.20

2.06

1.66

3.89

5.44

2.30

SD (pg/ml)

1.56

1.76

1.06

2.04

3.84

1.53

Summer

Mean (pg/ml)

2.09

1.95

1.81

3.15

5.97

2.32

SD (pg/ml)

1.74

1.31

1.62

2.05

3.68

1.53

Autumn

Mean (pg/ml)

2.12

1.91

1.88

3.03

5.24

2.47

SD (pg/ml)

1.54

1.51

1.64

1.68

3.83

1.21

Annual average

Mean (pg/ml)

2.39

2.03

1.84

3.61

5.73

2.69

SD (pg/ml)

1.47

1.38

1.50

3.34

5.08

2.58