Table 4 Detailed stimulus specification of the light interventions

From: Afternoon to early evening bright light exposure reduces later melatonin production in adolescents

 

Light intervention condition

 

Dim

Moderate

Bright

Sensor orientation

forward

forward

90°left

90° right

forward

forward

90°left

90° right

forward

forward

90°left

90° right

Measurement plane

vertical

45° down (book)

vertical

vertical

vertical

45° down (book)

vertical

vertical

vertical

45° down (book)

vertical

vertical

Illuminance (lx)

6.48

3.86

3.53

3.86

132.36

83.12

73.90

77.11

2545.94

1488.91

1389.34

1413.00

Melanopic EDI (lx)

3.69

2.19

2.00

2.21

84.04

52.00

45.65

47.71

1410.50

813.98

753.19

765.66

S-cone-opic EDI (lx)

4.40

2.59

2.30

2.54

97.44

59.16

51.24

53.85

1666.84

945.18

873.76

889.11

M-cone-opic EDI (lx)

5.61

3.34

3.06

3.35

115.41

72.29

64.08

66.96

2205.91

1287.58

1200.69

1220.11

L-cone-opic EDI (lx)

6.45

3.84

3.51

3.83

132.95

83.46

74.20

77.38

2524.59

1475.82

1376.36

1400.34

Rhodopic EDI (lx)

4.19

2.49

2.28

2.50

91.85

57.10

50.30

52.58

1623.60

941.45

873.86

887.92

Melanopic irradiance (mW ⋅ m−²)

4.90

2.91

2.66

2.93

111.46

68.96

60.54

63.27

1870.62

1079.51

998.89

1015.42

S-cone-opic irradiance (mW ⋅ m−²)

3.60

2.11

1.88

2.08

79.64

48.35

41.88

44.01

1362.29

772.48

714.12

726.66

M-cone-opic irradiance (mW ⋅ m−²)

8.17

4.86

4.45

4.88

168.02

105.24

93.30

97.48

3211.43

1874.49

1748.00

1776.26

L-cone-opic irradiance (mW ⋅ m−²)

10.51

6.26

5.72

6.24

216.57

135.95

120.87

126.04

4112.33

2403.98

2241.96

2281.02

Rhodopic irradiance (mW ⋅ m−²)

6.07

3.61

3.30

3.63

133.16

82.78

72.92

76.23

2353.73

1364.83

1266.84

1287.22

CIE 1964 x10y10 chromaticity [x10]

0.38

0.38

0.38

0.38

0.38

0.38

0.38

0.38

0.38

0.38

0.38

0.38

CIE 1964 x10y10 chromaticity [y10]

0.35

0.36

0.36

0.36

0.35

0.35

0.35

0.35

0.36

0.36

0.36

0.36

CCT (K) - Ohno, 2013

4040

4018

4022

4061

4010

3956

3904

3933

4058

4019

4014

4000

Colour Rendering Index [Ra]

80

80

80

80

87

87

87

87

80

79

79

79

  1. Summary of the spectral irradiance derived values for the 3 AEE light interventions (between 7.5 and 3 h before HBT) at different angles and reflectance scenarios. Measurements were taken vertically facing forward, 45° angled downwards with an open book on the table, and vertically, with the sensor 90° angled to the left and right. The subsequent evening light condition (from 3 h before HBT to 1.5 h after HBT) had the same characteristics as the ‘moderate’ light intervention. Participants were instructed and monitored to remain seated and keep their eyes open with their sitting posture directed forward. The spectral irradiance measurements were taken from the observer’s point of view with a research-grade spectroradiometer (Spectraval 1501, JETI Technische Instrumente GmbH, Jena, Germany). The sensor was placed at the eye level of the seated participants (115 cm from the floor, 85 cm from the overhead light source, 80 cm from the white curtain in front of them). Values used for stimulus specification include illuminance, alpha-opic equivalent daylight illuminances (alpha-opic EDIs), alpha-opic irradiances (given in mW ⋅ m−²), CIE 1931 xy chromaticity coordinates, Correlated Colour Temperature (CCT), and Colour Rendering Index (CRI). These values were calculated from spectral irradiance measurements using the luox application172.
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