The effects of short-term light exposure on subjective affect and comfort are dependent on the lighting time of day

AbstractLight, one of the key environmental components for both life and work, played significant role in subjective feelings (e.g. affect and comfort), but the exact effects and mechanisms were still to be determined. The present study screened thirty healthy adults (13 females, 22.45 ± 3.26 years) and examined subjective affect and comfort under short-term white lights with different combination of correlated color temperature (CCT) and illuminance at different times of day (e.g. morning, afternoon, and evening). Our results showed a significant interaction between illuminance level and time-of-day on subjective comfort. Participants felt more comfortable under 50 lx and 100 lx instead of 500 lx in the evening, and more comfortable under 500 lx in the morning and afternoon. In addition, a positive correlation between illuminance and comfort in the morning and a negative correlation between them in the evening were found. No significant effect of CCT on any subjective feeling was revealed. Our results necessitate the consideration of time-of-day in understanding lighting effects and application of healthy lighting in daily life.

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Time-of-day Dependent Light Effects on Subjective Affect and Comfort

10.21203/rs.3.rs-118101/v1 ◽

2020 ◽

Author(s):

Lijun Chen ◽

Fangfang Yan ◽

Shuhan Fan ◽

Yifan Wu ◽

Jia Yang ◽

...

Keyword(s):

Significant Role ◽

Negative Correlation ◽

Significant Interaction ◽

Daily Life ◽

Time Of Day ◽

Color Temperature ◽

Subjective Feeling ◽

Short Term ◽

Illuminance Level ◽

Light Effects

Abstract Light, one of the key environmental components for both life and work, played significant role in subjective feelings (e.g. affect and comfort), but the exact effects and mechanisms were still to be determined. The present study screened thirty healthy adults (13 females, 22.45 ± 3.26 years) and examined subjective affect and comfort under short-term white lights with different combination of correlated color temperature (CCT) and illuminance at different times of day (e.g. morning, afternoon, and evening). Our results showed a significant interaction between illuminance level and time-of-day on subjective comfort. Participants felt more comfortable under 50 lx and 100 lx instead of 500 lx in the evening, and more comfortable under 500 lx in the morning and afternoon. In addition, a positive correlation between illuminance and comfort in the morning and a negative correlation between them in the evening were found. No significant effect of CCT on any subjective feeling was revealed. Our results necessitate the consideration of time-of-day in understanding lighting effects and application of healthy lighting in daily life.

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Effects of Illuminance and Correlated Color Temperature on Daytime Cognitive Performance, Subjective Mood, and Alertness in Healthy Adults

Environment and Behavior ◽

10.1177/0013916517738077 ◽

2017 ◽

Vol 51 (2) ◽

pp. 199-230 ◽

Cited By ~ 11

Author(s):

Yingying Zhu ◽

Minqi Yang ◽

Ying Yao ◽

Xiao Xiong ◽

Xiaoran Li ◽

...

Keyword(s):

Cognitive Performance ◽

Light Exposure ◽

Bright Light ◽

Time Of Day ◽

Healthy Adults ◽

Color Temperature ◽

Future Research ◽

Long Term Memory ◽

Indoor Lighting ◽

The Impact

This study investigated the impact of indoor illuminance and correlated color temperature (CCT) on healthy adults’ cognitive performance, subjective mood, and alertness during daytime office hours and differences in time-of-day effects. A 2(illuminance) × 2(CCT) × 2(morning vs. afternoon) mixed design ( N = 60) was employed. Participants felt less sleepy in the bright light exposure. The low “cool” lighting induced the least positive mood. The effects of illuminance and CCT on subjective feelings were not time-of-day dependent. The results demonstrated the slowest responses in inhibition, working memory, and recognition of facial expression tasks in the low “warm” lighting. The effect on long-term memory was most pronounced under the high “cool” light exposure, but only in the afternoon for recognition of neutral words. The findings suggest that future research on good indoor lighting should consider illuminance levels and CCT as well as other variables to optimize lighting effects during regular daytime hours.

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PLACENTAL LACTOGEN IN THE GOAT IN RELATION TO STAGE OF GESTATION, NUMBER OF FETUSES, METABOLITES, PROGESTERONE AND TIME OF DAY

Journal of Endocrinology ◽

10.1677/joe.0.0860279 ◽

1980 ◽

Vol 86 (2) ◽

pp. 279-290 ◽

Cited By ~ 26

Author(s):

T. J. HAYDEN ◽

C. R. THOMAS ◽

SUSAN V. SMITH ◽

ISABEL A. FORSYTH

Keyword(s):

Fatty Acids ◽

Negative Correlation ◽

Time Of Day ◽

Radioreceptor Assay ◽

Daily Treatment ◽

Placental Lactogen ◽

Short Term ◽

Esterified Fatty Acids ◽

Normal Period

Placental lactogen has been measured in goats throughout pregnancy by radioreceptor assay of prolactin-like activity. Lactogenic activity, which is not prolactin, increased from less than 5 nmol/l in week 8 to 27 nmol/l by week 16. There was no further change until term. Plateau concentrations (week 16 to term) were highest in animals carrying triplets, 49·5 nmol/l. There were marked fluctuations in placental lactogen over a 24 h period. These short-term fluctuations were not related to changes in glucose, non-esterified fatty acids or, in two animals, progesterone. However, there was a negative correlation between mean concentrations of placental lactogen and glucose in plasma of 20 goats sampled over a 24 h period between weeks 15 and 20 of gestation. There was no difference in placental lactogen concentration from week 16 to term between goats in their first and second pregnancies although the normal period of increase in placental lactogen was delayed by some 3 weeks in goats in their second pregnancy. In hemimastectomized goats, hypophysectomy on day 60 did not affect placental lactogen but daily treatment with bromocriptine (5 mg/day) from day 60 to day 120 blocked the normal rise in concentration.

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Is the use of high correlated color temperature light at night related to delay of sleep timing in university students? A cross-country study in Japan and China

Journal of PHYSIOLOGICAL ANTHROPOLOGY ◽

10.1186/s40101-021-00257-x ◽

2021 ◽

Vol 40 (1) ◽

Author(s):

Shigekazu Higuchi ◽

Yandan Lin ◽

Jingjing Qiu ◽

Yichi Zhang ◽

Michihiro Ohashi ◽

...

Keyword(s):

Circadian Rhythm ◽

University Students ◽

Daily Life ◽

Light Exposure ◽

Chinese Students ◽

Color Temperature ◽

Light At Night ◽

Japanese Students ◽

Sleep Timing ◽

At Home

Abstract Background Blue-enriched white light at night has the potential to delay the circadian rhythm in daily life. This study was conducted to determine whether the use of high correlated color temperature (CCT) light at home at night is associated with delay of sleep timing in university students. Methods The survey was conducted in 2014–2015 in 447 university students in Japan and 327 students in China. Habitual sleep timing and type of CCT light at home were investigated by using a self-administered questionnaire. The Japanese students were significantly later than the Chinese students in bedtime, wake time, and midpoint of sleep. They were asked whether the lighting in the room where they spend most of their time at night was closer to warm color (low CCT) or daylight color (high CCT). The amount of light exposure level during daily life was measured for at least 1 week by the use of a light sensor in 60 students in each country. Results The percentages of participants who used high CCT lighting at night were 61.6% for Japanese students and 80.8% for Chinese students. Bedtime and sleep onset time on school days and free days were significantly later in the high CCT group than in the low CCT group in Japan. The midpoint of sleep in the high CCT group was significantly later than that in the low CCT group on free days but not on school days. On the other hand, none of the sleep measurements on school days and free days were significantly different between the high CCT and low CCT groups in China. Illuminance level of light exposure during the night was significantly higher in Japanese than in Chinese, but that in the morning was significantly higher in China than in Japan. Conclusions The use of high CCT light at night is associated with delay of sleep timing in Japanese university students but not in Chinese university students. The effects of light at night on sleep timing and circadian rhythm may be complicated by other lifestyle factors depending on the country.

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Aging and Different Prospective Memory Tasks in Daily Life: Event-Based, Short Term Time, Time of Day Tasks

PsycEXTRA Dataset ◽

10.1037/e528942014-310 ◽

2014 ◽

Author(s):

Peter Rendell ◽

Nathan Rose ◽

Susan Sapega ◽

Gill Terrett ◽

Phoebe E. Bailey

Keyword(s):

Prospective Memory ◽

Daily Life ◽

Time Of Day ◽

Short Term ◽

Life Event ◽

Event Based

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An Empirical Analysis of the Obtrusiveness of and Participants' Compliance with the Electronically Activated Recorder (EAR)

European Journal of Psychological Assessment ◽

10.1027/1015-5759.23.4.248 ◽

2007 ◽

Vol 23 (4) ◽

pp. 248-257 ◽

Cited By ~ 58

Author(s):

Matthias R. Mehl ◽

Shannon E. Holleran

Keyword(s):

Empirical Analysis ◽

Sampling Method ◽

Daily Life ◽

Assessment Method ◽

Data Confidentiality ◽

Short Term ◽

Naturally Occurring ◽

Two Samples ◽

Audio Recorder ◽

Term Monitoring

Abstract. In this article, the authors provide an empirical analysis of the obtrusiveness of and participants' compliance with a relatively new psychological ambulatory assessment method, called the electronically activated recorder or EAR. The EAR is a modified portable audio-recorder that periodically records snippets of ambient sounds from participants' daily environments. In tracking moment-to-moment ambient sounds, the EAR yields an acoustic log of a person's day as it unfolds. As a naturalistic observation sampling method, it provides an observer's account of daily life and is optimized for the assessment of audible aspects of participants' naturally-occurring social behaviors and interactions. Measures of self-reported and behaviorally-assessed EAR obtrusiveness and compliance were analyzed in two samples. After an initial 2-h period of relative obtrusiveness, participants habituated to wearing the EAR and perceived it as fairly unobtrusive both in a short-term (2 days, N = 96) and a longer-term (10-11 days, N = 11) monitoring. Compliance with the method was high both during the short-term and longer-term monitoring. Somewhat reduced compliance was identified over the weekend; this effect appears to be specific to student populations. Important privacy and data confidentiality considerations around the EAR method are discussed.

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