Lighting scheme recommendation for interior workplace to adjust the

phase-advance jet lag

Dandan Hou a,b

, Sijie He a

, Congshan Dai a

, Shaoping Chen c

, Huaming Chen c

, Yandan Lin a,b,*

a Institute for Electric Light Sources, School of Information Science and Technology, Fudan University, Shanghai, China b Institute of Future Lighting, Academy for Engineering and Technology, Fudan University, Shanghai, China c LEDVANCE Lighting (Shenzhen) Co., Ltd, Shenzhen, China

ARTICLE INFO

Keywords:

Light scheme

Jet lag

Circadian rhythms

Interior workplace

Daytime alertness

Sleep quality

ABSTRACT

Light has been found to affect the circadian clock of the human body. This study aims at exploring the proper

light scheme for improving performance and alleviating the negative effects of phase-advance jet lag. Herein, the

2.4.3. Circadian phase

Melatonin levels are covariates of the body’s rhythm phase. In

addition, the onset and offset times of melatonin production have been

clinically used to assess problems associated with sleep. Hence, DLMO

assessment is an effective analytical method for evaluating individual

phase delay or rhythm advance [63]. In this experiment, the melatonin

level is repeatedly tested to determine the time point of the DLMO. For

the periods and intervals of salivary melatonin, the method described in

Voultsios’s [64] and Pandi- Perumal’s [63] studies are adopted. The

sampling is started at 18:00 and continue until habitual bedtime. To

reduce the influence of individual differences and the cosine characteristics of melatonin levels on the DLMO threshold, the method of Parry

et al. to calculate the DLMO threshold [65] is referred, and the average

value of 18:00–20:00 in the melatonin baseline data are used as the

DLMO threshold. According to the linear interpolation results, the

DLMO time determined by this method is around 19:00 for each subject.

Therefore, our light intervention goal is that the DLMO time appears at

19:00 in the new time zone after the time zone conversion. It should be

noted that the DLMO time on the intervention day is assumed to have

occurred only when the melatonin level was higher than the threshold

for the three consecutive samplings. The time point of the DLMO is

defined as the first of the three consecutive samplings. If the DLMO on

the intervention day does not appear in the test period, it is suggested

that the DLMO occurred after 23:00, as a conservative estimate, 23:00

will be set as the DLMO time [66]. The melatonin level was measured

using the commercially available ELISA kit (Shanghai Keshun Biological

Technology Co., Ltd.). The intra-assay coefficient of variation (CV) was

less than 10%, and the inter-assay CV was less than 15%. The minimum

detectable dose in the human MT is typically less than 0.1 pg/mL.

2.5. Procedures

This is a double-blind, randomized between-subject design study

with baseline calibration. A 7-day circadian phase control and 4-day

closed circadian conversion experiment are performed. The 27 participants are randomly assigned to three groups (CLG, LIG, and HIG). In

each group, 9 participants perform the tasks independently of each

other, following the experimental process shown in Fig. 4. The circadian

phase control stage is conducted from day 1 to day 7. The subjects are

asked to limit their sleep time to 23:00–7:00 at home, which is close to

their original sleep time because all of them belonged to the “intermediate type" according to the MEQ. Their sleep intervals are monitored by

a smart wristband app (Huawei FIT 2, Huawei Device (Dongguan) Co.,

Ltd., China). The accuracy of the wristband has been verified by the

previous study [67]. If the subject violates the sleeping time by more

than 0.5 h, he/she will be disqualified.

The circadian phase conversion stage is conducted from day 8 to day

11, and each subject spends 63 h in the laboratory since his/her first

entrance to the laboratory at 14:00 on day 8. They are first provided preexperiment training in the activity room (14:00–17:00). The preexperiment includes explanations of the experimental procedures,

measurements, and announcements; training for cognitive tasks (five

times for each task). Melatonin is collected every 0.5 h for 11 times from

18:00 to 23:00 as the baseline data. The experimenters begin to assist

each subject in wearing the PSG device at 21:00. The participants

wearing the PSG device are allowed to move or rest in the sleeping room

but are prohibited from closing their eyes or sleeping until 23:00. The

experimenter turns off the lights in sleeping rooms and starts recording

the PSG device data at 23:00. At seven o’clock of the day 9, the experimenter turns on the lights and stops collecting data from the PSG device. The baseline data of alertness during the daytime (according to the

KSS) is collected 10 times during 8:00–12:00 and 13:00–17:00 of day 9

(once per hour). The eastward flight is simulated during 10:00–21:00

(real clock) of day 9. The boarding call is broadcast at 10:00 during the

simulated flight. The simulated flight ends at 21:00 (real clock);

everyone enters the new time zone at that time and their clocks were set

to “set clock," as shown in Fig. 3. Accordingly, in the new time zone, the

Fig. 4. Experimental procedure. The diagonal box indicates that the subjects are located in the activity room, the bright yellow box indicates that the subjects are

located in the light intervention room, and the dark gray box indicates that the subjects are located in the sleeping room. The orange line is the 0:00 a.m. line,

表示時區(qū)轉(zhuǎn)換。盒子下方顯示了不同測量值的彩色條:藍(lán)色表示褪黑激素收集，綠色表示PSG監(jiān)測，紅色表示警惕性測試。(讀者可以參考本文的Web版本來理解圖中顏色的含義。)