Demographic information
A total of 79 people participated in this study, and some of the participants had missing data, missing data were discarded in the statistical analysis. Among them, there were 71 males and 3 females, and gender information of the other five persons was missing. Regarding marital status, the number of single persons is 23, two individuals were divorced, 48 people were married. One person indicated “Other”, and data was missing from five participants. A number of 15 participants lived alone, 16 participants reported to live with their parents, and seven individuals lived with their partners, two people live with children only. There were 31 participants living with partners and children, 8 people had missing data. In terms of levels of education, two people have middle school education and below. A number of eight people have high school education. There are 29 people who finished undergraduate. 35 individuals completed graduate studies and above, and data from five participants is missing.
At baseline, 73 participants experienced mild depression or none (PHQ-9 scores ≤9), one person had moderate level of depression or above (PHQ-9 score ≥10). Participants’ GAD-7 scores indicated that 72 of them self-reported as experiencing mild anxiety or below (GAD scores ≤9). Two people experienced moderate level of anxiety and above (GAD scores ≥ 10). There were 62 people indicating acceptable sleep quality (PSQI scores ≤ 10), and three people had poor sleep quality (PSQI scoreS ≥ 11).
At the second week, 71 people experienced mild depression or none (PHQ-9 scores ≤9). One person had moderate level or above (PHQ-9 scores ≥10). A number of 70 participants had GAD-7 scores indicating mild anxiety or below (GAD-7 scores ≤9) , and two people were moderate or above (GAD scores ≥ 10). When it comes to sleep quality, 52 participants reported an acceptable level of sleep quality (PSQI scores ≤ 10), and 7 people had poor sleep quality (PSQI scores ≥ 11).
At the 8th week, 65 people reported to have mild depression or none (PHQ-9 scores ≤9), 2 had moderate level or above (PHQ-9 scores ≥10). GAD-7 scores showed that 64 people experienced mild anxiety or below (GAD-7 scores ≤9) , two people had moderate anxiety or above (GAD scores ≥ 10). Regarding sleep quality, a total of 55 people reported to have acceptable sleep quality (score ≤ 10), and five people had poor sleep quality (score ≥ 11).
Relationship between time, the latitude and GAD-7, PHQ-9, PSQI
In this scientific expedition itinerary, the latitude and longitude were recorded once every 6 hours. The average latitude during the first week was 41.03°±6.59°, the average latitude during the second week was 60.33°±6.72°, and the average latitude during the eighth week was 76.42°±1.21°. Over time, the latitude at which the scientific expedition team arrived continued to increase. The distribution of GAD-7, PHQ-9, and PSQI scores is not normally distributed. Therefore, Wilcoxon signed-rank test was used. There were no statistically significant differences in GAD-7 scores between different time period (baseline, week 2 and week 8). The There was a statistically significant difference in PHQ-9 scores between baseline and the 8th week. At baseline, the median of PHQ-9 scores was 2 and that at week 8 was 3. Wilcoxon signed-rank test showed that Z=-2.768, P<0.05. However, there were no statistically significant differences between baseline and the 2nd week, the 2nd and the 8th week in PHQ-9 scores. The PSQI scores showed a statistical difference between baseline and the 2nd week. The median score of PSQI at baseline was 5 and the median at the 2nd week was 5. Wilcoxon signed-rank test showed that Z=-2.104, P <0.05. However, there were no statistically significant differences in PSQI scores between baseline and the 8th week, the 2nd week and the 8th week.
This study also explored the PSQI subscales, and found that statistical differences existed in sleep latency between baseline and the 2nd week, the 2nd and the 8th week, Z=-3.748, Z=-2.436 respectively. There were statistical differences in sleep duration between baseline and the 2nd week, baseline and the 8th week, and between the 2nd and 8th week, Z=-2.179, Z=-2.745, Z=-3.947 respectively. Statistical differences in daytime dysfunction existed only between baseline and the 8th week, Z=-2.408 (Figure 1).
Relationship between time, latitude and different symptomatic groups of PHQ-9, GAD-7, PSQI
Cochran's Q test was used to explore the similarities and differences among different symptomatic groups of PHQ-9, GAD-7 and PSQI at different time and latitudes. The results showed that based on PHQ-9 scores, a total of 62 participants were included. The percentages of the symptomatic group at baseline, the 2nd and 8th week were 25.8%, 30.6%, and 37.1%, respectively, χ2=5.286, p=0.071>0.05. There were no significant differences at these three time points for the symptomatic group. Based on scores on GAD-7, a total of 61 participants were included. The proportions of the symptomatic group at baseline, the 2nd and 8th week were 14.8%, 21.3%, and 19.7%, respectively, χ2=1.733, p=0.42>0.05. There were no significant differences at these three time points for the symptomatic group. Based on PSQI scores, 43 people were included. The proportions of the symptomatic group at baseline, the 2nd and 8th week were 34.9%, 37.2%, and 44.2%, respectively, χ2=2, p=0.368 >0.05. There were no significant differences at these three time points for the symptomatic group (Figure 2).
Personal characteristics and emotional changes in the polar environment
Relationship between personal background information and PHQ-9, GAD-7, PSQI and its subscales
This study also explored the influence of personality traits on mood and sleep conditions, and investigated whether different individual characteristics play a role in changes in mood and sleep. A total of 29 people completed the relevant assessments, and the missing data were discarded. This study applied a generalized linear mixed model to analyze data from repeated measures. The following factors were taken into consideration: age, marital status, level of education, current living conditions, personality traits, and coping styles.
The results indicated that the model exploring relations between PHQ-9 scores and personal background information such as age, marital status, education level, personal income and current living conditions etc., was not statistically significant. The relation between marital status and GAD-7 scores was statistically significant (F=5.065, p<0.05). Specifically, singleness was associated with lower scores on GAD-7. Personal conditions and the PSQI total scores were not related in a statistically significant way, instead were related to the subscales of PSQI significantly, including sleep quality, sleep latency, sleep duration, and sleep efficiency (Table 1, Table 2). Pairwise comparison indicated that compared with individuals with income> 10,000 RMB per capita, those with an income of 5,000-10,000 RMB per capita had worse sleep quality. (coefficient 0.52, p<0.05). In terms of sleep latency, compared with individuals having an income> 10,000 RMB and a graduate degree or above, those with an income of 5,000-10,000 RMB per capita (coefficient 1.002, p<0.05), and a bachelor degree (coefficient 0.75, p<0.05) had longer sleep latency while those with a high school education (coefficient -0.87, p<0.05) had shorter sleep latency. With the increase of age (coefficient 0.04, p<0.01), the total sleep duration decreases gradually. Those with an undergraduate degree (coefficient 0.38, p<0.03) had shorter duration of sleep time compared with participants with high school education (coefficient -0.54, p<0.05). In terms of sleep efficiency, with the increase in age (coefficient -0.07, p<0.05), sleep efficiency improved. People living alone (coefficient -1.71, p<0.05), living with parents (coefficient -1.84, p<0.05) experienced better sleep efficiency than those living with partners and children. People who had an income <5000 RMB (coefficient -0.94, p<0.05) and those with an income between 5000-10000 RMB (coefficient -0.77, p<0.05) had better sleep efficiency than individuals having an income greater than 10,000 RMB.
Table 1 The influence of personal background information on PHQ-9, GAD-7, PSQI
|
PHQ-9
|
GAD-7
|
PSQI
|
F
|
p
|
F
|
p
|
F
|
p
|
Calibration model
|
1.11
|
0.37
|
1.91
|
0.07
|
1.17
|
0.33
|
Age
|
0.91
|
0.34
|
1.78
|
0.19
|
1.26
|
0.27
|
Marital status
|
0.75
|
0.39
|
5.07
|
0.03*
|
0.00
|
0.98
|
Living conditions
|
0.23
|
0.88
|
0.68
|
0.57
|
0.68
|
0.57
|
Salary
|
0.43
|
0.65
|
0.34
|
0.72
|
2.69
|
0.08
|
Education
|
1.77
|
0.18
|
1.76
|
0.18
|
0.46
|
0.64
|
*p<0.05
Table 2 The influence of personal background information on PSQI subscales
|
sleep quality
|
sleep latency
|
sleep duratio-n
|
sleep efficien-cy
|
sleep disturba-nce
|
daytime dysfuncti-on
|
F
|
p
|
F
|
p
|
F
|
p
|
F
|
p
|
F
|
p
|
F
|
p
|
Calibra-tion model
|
1.24
|
0.28
|
4.78
|
0.00*
|
3.83
|
0.00*
|
1.95
|
0.06
|
1.14
|
0.35
|
2.01
|
0.05
|
Age
|
0.00
|
0.96
|
0.84
|
0.36
|
7.08
|
0.01*
|
8.62
|
0.00*
|
0.20
|
0.66
|
1.94
|
0.17
|
Marital status
|
0.30
|
0.59
|
0.00
|
0.99
|
2.29
|
0.14
|
3.42
|
0.07
|
0.05
|
0.82
|
0.52
|
0.47
|
Living conditio-ns
|
0.16
|
0.93
|
0.240
|
0.87
|
1.78
|
0.16
|
2.91
|
0.04*
|
1.31
|
0.28
|
2.07
|
0.11
|
Salary
|
4.59
|
0.01*
|
15.41
|
0.00*
|
1.90
|
0.16
|
3.44
|
0.04*
|
1.11
|
0.34
|
0.03
|
0.97
|
Educatio-n
|
1.64
|
0.20
|
6.97
|
0.00*
|
5.88
|
0.00*
|
1.38
|
0.26
|
1.56
|
0.22
|
2.48
|
0.09
|
*p<0.05
Relationships between personality traits and PHQ-9, GAD-7, PSQI and its subscales
The model of personality traits and PHQ-9 scores is of statistical significance (F=2.18, p<0.05). The higher the score of Factor Q4 Tension (coefficient of 0.59, p<0.05), the higher the score of PHQ-9 is. Personality traits are related to GAD-7 scores in a statistically significant way (F=3.40, p<0.05). Higher scores of Factor A Warmth (coefficient -0.27, p<0.05), and Factor E Dominance (coefficient -0.24, p<0.05) are correlated with lower scores on GAD-7. Scores of Factor F Liveliness (coefficient 0.43, p<0.05), factor M Abstractedness (coefficient 0.20, p<0.04), and Factor N Privateness (coefficient 0.21, p<0.03) are positively correlated with GAD-7 scores. The model based on the relations between personality traits and PSQI scores is of statistical significance (F=3.55, p<0.05). Factor L Vigilance (coefficient -0.38, p<0.05) is negatively correlated with PSQI score, Factor M Abstractedness (coefficient 0.41, p<0.05), Factor Q3 Perfectionism (coefficient 0.723, p<0.05), and Factor Q4 Tension (coefficient 1.19, p<0.05) are positively correlated with PSQI scores (Table 3).
Table 3 The influence of personality traits on PHQ-9, GAD-7, PSQI
|
PHQ-9
|
GAD-7
|
PSQI
|
F
|
p
|
F
|
p
|
F
|
p
|
Calibration model
|
2.18
|
0.02*
|
3.40
|
0.00*
|
3.55
|
0.00*
|
a
|
0.01
|
0.94
|
6.42
|
0.01*
|
0.05
|
0.82
|
b
|
0.28
|
0.60
|
1.80
|
0.18
|
0.07
|
0.79
|
c
|
0.78
|
0.38
|
2.72
|
0.10
|
0.34
|
0.56
|
e
|
0.12
|
0.73
|
7.05
|
0.01*
|
1.78
|
0.19
|
f
|
2.13
|
0.15
|
15.14
|
0.00*
|
1.06
|
0.31
|
g
|
0.00
|
0.99
|
0.79
|
0.38
|
0.94
|
0.34
|
h
|
2.17
|
0.15
|
1.29
|
0.26
|
0.02
|
0.90
|
i
|
0.37
|
0.55
|
0.09
|
0.76
|
0.11
|
0.75
|
l
|
0.10
|
0.55
|
3.37
|
0.07
|
4.85
|
0.03*
|
m
|
2.04
|
0.16
|
4.23
|
0.04*
|
6.26
|
0.02*
|
n
|
0.57
|
0.45
|
5.06
|
0.03*
|
1.10
|
0.30
|
o
|
0.01
|
0.91
|
2.18
|
0.15
|
0.01
|
0.92
|
Q1
|
3.96
|
0.05
|
1.87
|
0.18
|
1.91
|
0.17
|
Q2
|
0.21
|
0.65
|
2.67
|
0.11
|
0.02
|
0.89
|
Q3
|
0.05
|
0.83
|
0.76
|
0.39
|
6.95
|
0.01*
|
Q4
|
5.18
|
0.03*
|
0.90
|
0.35
|
19.57
|
0.00*
|
*p<0.05
This study also explored the relationships between personality traits and the PSQI subscale. It was found that different personality traits have an impact on multiple subscales, including sleep quality, sleep latency, sleep duration, sleep efficiency, and sleep disturbances (Table 4). Factor Q4 Tension (coefficient 0.21, p<0.05) score is positively correlated with sleep quality score. Factor L Vigilance (coefficient -0.15, p<0.05), Factor N Privateness (coefficient -0.12, p<0.05) score and sleep latency score is negatively correlated. Factor M Abstractedness (coefficient 0.06, p<0.05), Factor Q3 Perfectionism (coefficient 0.19, p<0.05), Factor Q4 Tension (coefficient 0.22, p<0.05) score are positively correlated with sleep duration score. However, the scores of the following factors are negatively correlated with sleep duration, including Factor B Reasoning (coefficient -0.09, p<0.05), Factor C Emotional Stability (coefficient -0.07, p<0.05), Factor F Liveliness (coefficient -0.08, p<0.05), Factor I Sensitivity (coefficient -0.09, p<0.05), Factor O Apprehension (coefficient -0.12, p<0.05), and Factor Q1 Openness to Change (coefficient -0.07, p<0.05). The scores of the following factors are positively related to sleep efficiency scores, Factor B Reasoning (coefficient 0.18, p<0.05), Factor F Liveliness (coefficient 0.20, p<0.05), Factor M Abstractedness (coefficient 0.16, p<0.05), Factor N Privateness (coefficient 0.09, p<0.05), Factor Q1 Openness to Change (coefficient 0.12, p<0.05), Factor Q3 Perfectionism (coefficient 0.33, p<0.05), Factor Q4 Tension (coefficient 0.29, p<0.05). Whereas, scores of Factor E Dominance (coefficient -0.17) , P<0.05), and Factor L Vigilance (coefficient -0.13, p<0.05) are negatively correlated with sleep efficiency scores. Scores of the following factors are positively related to scores on the sleep disturbance subscale, Factor F Liveliness (coefficient 0.08, p<0.05), Factor M Abstractedness (coefficient 0.09, p<0.05) 0.05), Factor N Privateness (coefficient 0.07, p<0.05), Factor Q2 Self-Reliance (coefficient 0.07, p<0.05). Whereas scores of Factor A Warmth (coefficient -0.08, p<0.05) ), Factor B Reasoning (coefficient -0.12, p<0.05), Factor E Dominance (coefficient -0.07, p<0.05), Factor I Sensitivity (coefficient -0.08, p<0.05) are negative correlated with sleep disturbance scores.
Table 4 The influence of personality traits on PSQI subscales
|
sleep quality
|
sleep latency
|
sleep duration
|
sleep efficienc-y
|
sleep disturba-nce
|
daytime dysfunct-ion
|
F
|
p
|
F
|
p
|
F
|
p
|
F
|
p
|
F
|
p
|
F
|
p
|
Calibra-tion model
|
2.08
|
0.02*
|
3.37
|
0.00*
|
3.58
|
0.00*
|
5.35
|
0.00*
|
4.12
|
0.00*
|
3.52
|
0.00
|
a
|
0.60
|
0.44
|
2.27
|
0.14
|
0.06
|
0.81
|
2.62
|
0.11
|
8.93
|
0.00*
|
0.01
|
0.93
|
b
|
2.79
|
0.10
|
0.93
|
0.34
|
4.68
|
0.03*
|
8.54
|
0.01*
|
14.14
|
0.00*
|
4.20
|
0.045
|
c
|
0.14
|
0.71
|
0.20
|
0.65
|
4.20
|
0.045*
|
0.87
|
0.35
|
0.61
|
0.44
|
7.24
|
0.01
|
e
|
0.01
|
0.92
|
0.02
|
0.89
|
1.52
|
0.22
|
14.99
|
0.00*
|
11.89
|
0.00*
|
0.66
|
0.42
|
f
|
0.49
|
0.49
|
0.47
|
0.50
|
5.26
|
0.03*
|
12.32
|
0.00*
|
8.90
|
0.00*
|
0.59
|
0.45
|
g
|
0.61
|
0.44
|
0.84
|
0.36
|
0.17
|
0.68
|
0.69
|
0.41
|
3.39
|
0.07
|
1.46
|
0.23
|
h
|
0.28
|
0.60
|
1.01
|
0.32
|
0.28
|
0.60
|
1.50
|
0.23
|
2.02
|
0.16
|
1.51
|
0.22
|
i
|
1.67
|
0.20
|
3.26
|
0.08
|
8.27
|
0.01*
|
0.24
|
0.63
|
0.94
|
0.34
|
0.50
|
0.48
|
l
|
0.45
|
0.51
|
5.75
|
0.02*
|
0.82
|
0.37
|
6.04
|
0.02*
|
8.48
|
0.01*
|
0.93
|
0.34
|
m
|
0.00
|
0.98
|
1.73
|
0.19
|
4.04
|
0.049*
|
10.28
|
0.00*
|
14.26
|
0.00*
|
0.32
|
0.58
|
n
|
0.00
|
0.98
|
4.71
|
0.03*
|
1.41
|
0.24
|
4.19
|
0.045*
|
10.70
|
0.00*
|
5.91
|
0.02
|
o
|
0.00
|
0.97
|
1.98
|
0.16
|
6.81
|
0.01*
|
0.38
|
0.54
|
0.15
|
0.70
|
0.52
|
0.47
|
Q1
|
0.13
|
0.73
|
0.01
|
0.92
|
4.94
|
0.03*
|
7.17
|
0.01*
|
2.42
|
0.13
|
10.57
|
0.00
|
Q2
|
1.76
|
0.19
|
0.76
|
0.39
|
3.71
|
0.06
|
0.05
|
0.83
|
6.50
|
0.01*
|
0.01
|
0.93
|
Q3
|
1.90
|
0.17
|
0.31
|
0.58
|
12.70
|
0.00*
|
15.45
|
0.00*
|
0.59
|
0.44
|
0.61
|
0.44
|
Q4
|
8.10
|
0.01*
|
2.24
|
0.14
|
15.23
|
0.00*
|
12.14
|
0.00*
|
0.01
|
0.92
|
9.79
|
0.00
|
*p<0.05
Relationships between coping styles and PHQ-9, GAD-7, PSQI and its subscales
The relations between coping styles and PHQ-9, GAD-7 and PSQI scores have statistical significance (Table 5). Further analysis showed that coping styles have an impact on sleep quality, sleep disturbances and daytime dysfunction. The help-seeking factor (coefficient 0.91, p<0.05) is positively correlated with the sleep quality score; the problem-solving factor (coefficient -1.46, p<0.05) is negatively correlated with the sleep disturbance score, and the help-seeking factor (coefficient 0.77, p<0.05) is positively correlated with the score of sleep disturbance. The self-blaming factor (coefficient 3.08, p<0.05) is positively correlated with the daytime dysfunction score (Table 6).
Table 5 The influence of coping styles on PHQ-9, GAD-7, PSQI
|
PHQ-9
|
GAD-7
|
PSQI
|
F
|
p
|
F
|
p
|
F
|
p
|
Calibration model
|
2.86
|
0.02*
|
3.13
|
0.01*
|
2.46
|
0.03*
|
Problem-solving
|
1.44
|
0.23
|
0.03
|
0.87
|
0.70
|
0.41
|
Self-blaming
|
0.97
|
0.33
|
1.35
|
0.25
|
1.71
|
0.20
|
Help-seeking
|
0.07
|
0.79
|
1.22
|
0.27
|
1.05
|
0.31
|
Fantasy
|
0.65
|
0.42
|
0.30
|
0.59
|
0.03
|
0.87
|
Withdrawing
|
1.04
|
0.31
|
3.52
|
0.07
|
2.21
|
0.14
|
Rationalization
|
0.63
|
0.43
|
0.98
|
0.33
|
0.05
|
0.83
|
*p<0.05
Table 6 The influence of coping styles on PSQI subscales
|
sleep quality
|
sleep latency
|
sleep duration
|
sleep efficienc-y
|
sleep disturbanc-e
|
daytime dysfunctio-n
|
F
|
p
|
F
|
p
|
F
|
p
|
F
|
p
|
F
|
p
|
F
|
p
|
Calibration model
|
2.84
|
0.02*
|
1.81
|
0.11
|
0.29
|
0.94
|
0.63
|
0.71
|
2.97
|
0.01*
|
5.59
|
0.00*
|
Problem-solving
|
1.44
|
0.24
|
3.28
|
0.08
|
0.63
|
0.43
|
0.40
|
0.53
|
7.50
|
0.01*
|
0.11
|
0.74
|
Self-blaming
|
3.01
|
0.09
|
0.83
|
0.37
|
0.10
|
0.75
|
0.31
|
0.58
|
0.72
|
0.40
|
8.44
|
0.01*
|
Help-seeking
|
4.68
|
0.03*
|
1.66
|
0.20
|
0.13
|
0.72
|
0.03
|
0.87
|
6.56
|
0.01*
|
0.26
|
0.61
|
Fantasy
|
0.34
|
0.56
|
0.00
|
0.94
|
0.00
|
1.00
|
1.24
|
0.27
|
0.42
|
0.52
|
3.51
|
0.07
|
Withdrawing
|
2.84
|
0.10
|
0.15
|
0.70
|
0.99
|
0.32
|
3.54
|
0.06
|
1.94
|
0.17
|
1.51
|
0.22
|
Rationalization
|
0.33
|
0.57
|
2.19
|
0.14
|
0.04
|
0.85
|
0.36
|
0.55
|
1.71
|
0.20
|
0.46
|
0.50
|
*p<0.05