Table 2 Summary of the studies on the nonvisual effects of the light intensity in the field of physiological anthropology published in the JPA from 1992 to 2018 (data from January to October were obtained in 2018)

Higuchi S, Watanuki S, Yasukouchi A, Sato M. [45]

Luminance: 10, 100, 320, 1000, 1800 cd/m²

Color temperature: 2800 K

(tungsten lamp with diffuser and filters)

·CNV

·EEG

Park SJ, Tokura H. [33]

Illuminance: 200, 5000 lx

(fluorescent lamp)

Exposure time: 06:30–19:30

·Rectal temperature

Noguchi H, Sakaguchi T, Sato M. [46]

Illuminance: 0.5, 1, 3, 10, 30 lx

Color temperature: 3000 K

(fluorescent lamp)

Exposure time: 2 min

·Subjects: young, elderly

·Time slots of experiment 09:00–10:30, 10:30–12:00, 13:00–14:30, 14:30–16:00, 16:00–17:30

·HRV·EEG

·Subjective evaluation (discomfort)

Kim HE, Tokura H. [51]

Illuminance: 50, 3000 lx

(fluorescent lamp)

Exposure time: 09:30–14:30

Air temp.: 30 to 15 °C during 15:00–17:00

Elderly subjects

·Rectal temperature

·Skin temperature

·Blood pressure

·Heart rate

·Dressing behavior

·Subjective evaluation (temperature sensation, thermal comfort)

Kanikowska D, Hirata Y, Hyun K, Tokura H. [34]

Illuminance: 100, 3000 lx

(fluorescent lamp)

Exposure time: 07:00–18:00

first and second days: 100 lx, third day 3000 lx

·Rectal temperature

·Melatonin

·C-reactive protein

·α1-antichymotrypsin

·Transferrin

·α2-macroglobulin

·Haptoglobin

·Ceruloplasmin

Wakamura T, Tokura H. [35]

Illuminance: 3000 lx

Color temperature: 5000 K

(fluorescent lamp)

Exposure time: 10:00–15:00

Ambient light: 50–300 lx

Subjects, 7 hospitalized elderly patients

·Melatonin

·Bed time, get up time, time in bed, sleep start, sleep end, actual sleep time, immobile mins

Yokoi M, Aoki K, Shimomura Y, Iwanaga K, Katsuura T. [36]

Illuminance: 120, 2800 lx

(fluorescent lamp)

Exposure time: 21:00–04:30 during sleep deprivation

Stroop color-word conflict test

·Melatonin

·Rectal temperature

·Skin temperature

·EEG

·Subjective sleepiness

Tokura H, Kim HE. [52]

Illuminance: 10, 4000 lx

Exposure time: 10:00–18:00

Illuminance: 10, 3000 lx

Exposure time: 16:00–23:00

Air temp.: 30 to 15 °C during 20:30–22:30

Air temp.: 30 to 15 °C during 21:00–22:00

·Dressing behavior

·Rectal temperature

·Skin temperature

·Melatonin

·Subjective evaluation (temperature sensation, thermal comfort)

Higuchi S, Motohashi Y, Maeda T, Ishibashi K. [37]

Illuminance: 1000 lx during 2 h from 2 h before peak melatonin concentration

·Melatonin

·Questionnaire (Morningness-Eveningness Questionnaire)

·Sleep diary (bedtime, rising time, sleep quality, etc.)

Yokoi M, Aoki K, Shimomura Y, Iwanaga K, Katsuura T. [38]

Illuminance: 120, 2800 lx

(fluorescent lamp)

Exposure time: 21:00–04:30 during sleep deprivation

Stroop color-word conflict test

·Melatonin

·Rectal temperature

·Blood pressure

·Heart rate

·HRV

·Task performance

Hyun KJ, Nishimura S, Tokura H. [39]

Illuminance: 80, 5000 lx

Second day: 07:00–23:00 in 80 lx

Third day: 07:00–15:00 in 5000 lx, 15:00–23:00 in 80 lx

·Urine volume

·Creatinine clearance

Yasukouchi A, Hazama T, Kozaki T. [48]

PLR measurement:

Illuminance: 1, 3, 30, 600 lx

5-min light exposure during 01:00–02:30

Melatonin measurement:

Illuminance: 0, 30, 600 lx

Exposure time: 01:00–02:30

Green (530 nm) (LED)

·PLR

·Melatonin

·Oral temperature

·Blood pressure

Hirota N, Sone Y, Tokura H. [40]

Illuminance: 2000 lx

Exposure time: 07:00–15:00

Illuminance: 50, 2000 lx

Exposure time: 15:00–24:00

(fluorescent lamp)

·Breath hydrogen production (unabsorbed dietary carbohydrates)

Kozaki T, Toda N, Noguchi H, Yasukouchi A. [41]

Illuminance: 750, 1500, 3000, 6000, 12,000 lx

Color temperature: 5000 K

(fluorescent lamp)

Exposure time: 09:00–12:00

·Melatonin (DLMO)

·aMT6s concentration

Yoshinaga N, Fujita M, Tanaka YL, Nemoto S. [47]

Illuminance: 0, 50, 200 lx

Same, lowering and raising illuminance conditions

Exposure time: 2 min + 2 min

(fluorescent lamp)

Time zone of experiment: 11:00–17:00

·Somatosensory evoked potential (SEP)

·Subjective evaluation (pain)

Kakitsuba N, Mekjavic IB, Katsuura T. [49]

Illuminance:

1050 lx in winter

510 lx in summer and winter

Color temperature: 5000 K

(fluorescent lamp)

·Exercise: cycle ergometer (50% maximum work)

·Maintained mean skin temperature at 28 °C by perfusing a water-perfused suit with water at 25 °C.

·Core interthreshold zone (CIZ)

·Rectal temperature

·Skin temperature

·Sweat rate

·Oxygen uptake

Fukushige H, Fukuda Y, Tanaka M, Inami K, Wada K, Tsumura Y, Kondo M, Harada T, Wakamura T, Morita T. [42]

Illuminance: > 5000 lx (Bright), < 50 lx (Dim)

Exposure time: 07:30–18:00

Tryptophan intake:

Rich 476 mg

Poor 55 mg

Poor*dim, Poor*bright, Rich*dim, Rich*bright

·Melatonin (DLMO)

·Activity (sleep efficiency, sleep latency)

·Subjective estimation (sleepiness, sleep maintenance, worries, integrated sleep feeling, sleep initiation)

Kozaki T, Kubokawa A, Taketomi R, Hatae K. [43]

·Daytime

Illuminance: < 10, 100, 300, 900, 2700 lx

Exposure time: 09:00–12:00

·Nighttime

Illuminance: 300 lx

Exposure time: 01:00–02:30

(fluorescent lamp)

Color temperature: 4523 K

·Melatonin (DLMO)

Nagashima S, Yamashita M, Tojo C, Kondo M, Morita T, Wakamura T. [44]

Illuminance: 50 lx (dim), 5000 lx (bright)

Exposure time: 07:00–18:00

TRP*bright, placebo*bright, TRP*dim, and placebo*dim

Tryptophan (TRP) intake at breakfast

·Melatonin (DLMO)

Schobersberger W, Blank C, Hanser F, Griesmacher A, Canazei M, Leichtfried V. [50]

Illuminance:

5000 lx, 6500 K (bright light)

< 150 lx, 6500 K (office light)

Exposure time: 30 min (07:40–08:10)

(fluorescent lamp)

Sensorimotor and visuomotor performance tests

·6-sulfatoxymelatonin (aMT6s)

·Tryptophan

·Kynurenine

·Reaction times