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diurnal variations of hormonal secretion, alertness and cognition in extreme chronotypes under different lighting conditions

by:Grade     2020-01-22
Circadian rhythms in physiology and behavior are regulated by external factors such as light or temperature.
We studied.
Selected office lighting during habitual awake has different effects on alertness, cognitive ability and hormone secretion of extreme morning and evening time types (Nu2009=u200932)
Who\'s the preferred bedand wake-
The rise time varies by several hours. The self-
The selected lighting conditions were compared with the control conditions under constant bright light and dim light.
Saliva samples, alertness, well-being, visual comfort, and subjective scores of cognitive performance were collected regularly.
Between the self
Selection and bright, but not dim light conditions, the beginning of melatonin secretion at night (
As a marker for the circadian phase)
There are significant differences for both time types.
It is reported that the type of sleep in the morning increased faster than the type of sleep in the evening, which is related to high levels of cortical hormone secretion.
Happiness, mood and performance are better in intelligence and self in more difficult cognitive tasks
For both time types, the chosen lighting is better than the dim lighting, while the visual comfort is best in the self
Choose lighting.
To sum up, self
The choice of lighting at work may have a positive impact on biological and cognitive functions and allow for mutual
Individual Differences.
Three different lighting conditions were accepted by all participants (
Three different meetings. in a within-
Theme design across four seasons;
In continuous posture conditions, each training lasted 16 hours.
The first meeting is always carried out in dim light and serves as a condition of control.
The lighting conditions of the two experiments are constant glare (1000 lx)and self-
Choose lighting.
These two conditions are balanced.
Cross design.
The three meetings were held in three to six days. Thirty-
Two participants
16 Extreme morning types (MT);
16 extreme late types (ET);
14 males and 18 females; mean age 22. 7u2009±u20093. 5 years; (±SD)
Between the ages of 18 and 31; see ]
All 3 studies were completed.
The research procedure was approved by the local ethics review committee of Lausanne (Switzerland)
And agreed with the principles of the Helsinki Declaration.
Written informed consent is provided by all participants.
Subjects were asked to maintain normal sleep seven days before each study
Wake-up rhythm-about 8 hours of sleep, within 30 minutes of self-sleep
According to the sleeping time they habitually choose, choose the target time.
Compliance is controlled by the Activity Monitor wearing the wrist (Daqtix, Oetzen-
Seedorf, Germany)and sleep logs.
On the way to the lab in the morning, participants wore dark goggles to avoid exposure to bright light before the study.
Every study (see )
Plan to start one hour after designated habitual subjective wake-uptime [
= Circadian rhythm time 1 (CT 1)]
It lasted 16 hours (end of CT 16).
During the study, the participants were still sitting in the test room.
They are allowed to read, perform paper works or listen to music (
Including one hour of computer work scheduled during the day).
The research programmes for all three meetings are the same.
Every 30 minutes, participants were asked to evaluate their subjective well-being, mood and drowsiness on the visual analog scale (VAS; see ).
A cognitive test is performed with two alternating test batteries per hour (
8 times per person per day).
We used hearing and vision n-
Two continuous attention tests.
Mental exercise alert test (PVT)and the Go-no-go test; see also the ].
After each cognitive test battery, participants were asked to evaluate the mental effort they needed to perform the test on the mental effort rating scale (MERS; see ).
About 15 minutes after the end of each cognitive test battery, saliva samples were collected for hormone analysis.
Dim conditions of light (
= Control conditions for low light intensity)
E is less than 5 lx and only indirect lights are used.
The goal is to maintain a constant glare condition E at 1000 lx.
We use daylight, and when daylight is not enough, we use a multi-color white light ceiling lamp (4000u2009K)
Is turned on to provide the target illumination.
The constant E of 1000 lx was selected according to the literature affected by light irradiation, with the aim of providing a highly saturated condition for a non-saturated state
Visual function (
= High strength control conditions).
In the process of self
Participants can select daylight and/or light from all available sources (
See for details)
The maximum E provided by electrical lighting is about 1200 lx.
Illumination and color temperature depend on the selection of subjects.
Participants were asked to evaluate their lighting preferences every 60 minutes and then adjust accordingly.
Vision and contrast are evaluated every two hours, and visual comfort is evaluated every 30 minutes with a visual analog scale (see ).
Saliva samples were collected 15 minutes an hour after the cognitive test was completed for hormone concentration analysis.
Based on the timing of the increase in melatonin concentrations in dim light at night during the first session, we evaluated the onset of melatonin in dim light (DMLO).
DLMO is defined as the time when the saliva melatonin concentration exceeds the minimum 3 daytime values plus the threshold of 2 SD and is calculated by linear interpolation using a software tool validated by Danilenko. .
Several day and night phase angles were calculated to indicate the interval between habitual DLMO and bedtime, wake-up time, and mid-sleep (
Based on MSF-Sc).
Vision and contrast are evaluated every two hours, and visual comfort is evaluated every 30 minutes with a visual analog scale (see ).
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