Abstract
Sleep loss is a prevalent phenomenon in many cities, such as Hong Kong. The effects of sleep loss on cognitive and emotional functions have been widely studied, but only a few studies have examined the impact of sleep loss on social functions. This thesis aimed to investigate the effect of one night of total sleep deprivation on social decision-making and its neural basis as evidenced by electroencephalographic (EEG) indices.
Study 1 examined the effect of one night of sleep deprivation on social decision-making using a between-subjects design. Forty-three healthy participants were randomly assigned to the sleep deprivation (SD) or sleep control (SC) group. After a week of habitual sleep at their own residences, participants in the SD group stayed awake in the laboratory for one night, while those in the SC group slept normally at home. In the morning after the sleep condition (SD/SC), all the participants underwent an 8-minute resting-state EEG recording and completed tasks related to sleepiness, vigilance and social decision-making. The following two EEG indices related to the emotional regulatory and cognitive process were calculated: frontal alpha asymmetry (the frontal alpha power difference between the right and left hemispheres) and the frontal theta/beta ratio (the power ratio of theta and beta bands over the frontal regions). The results showed marginal significance in the left-lateralized frontal alpha power following SD, suggesting a trend of poorer emotional regulation ability after sleep loss. However, there was no significant difference in the frontal theta/beta ratio between the SD and SC groups. Moreover, the effect of SD on trust was moderated by depressive symptoms. Compared to the controls, participants with a higher level of depressive symptoms showed fewer trusting behaviors after SD, while participants with a lower level of depressive symptoms showed more trusting behavior after SD. However, there was no significant difference in rational decision-making performance between the SD and SC groups.
Considering individual differences in vulnerability to SD, Study 2 was conducted to examine the effect of one night of SD on social decision-making using a within-subjects design. Forty-eight participants completed a counterbalanced repeated-measures study design involving a night of SD and a night of normal sleep (NS), 7 days apart in a counterbalanced order. The participants completed an 8-minute resting-state EEG recording and measures of sleepiness, vigilance and social decision-making after each
sleep condition (SD/NS). Contrary to the prediction, the trend of significant left-lateralized frontal alpha power after SD and the interaction effect between SD and depressive symptoms on trust found in Study 1 were not detected in Study 2, which showed no other significant effects, suggesting that 24 h of SD may not have robust effects on resting-state EEG indices and social decision-making.
Overall, this study provides the first evidence of the moderation effect of depressive symptoms on the relationship between SD and trust. The results show that people who have a higher level of depressive symptoms are more vulnerable to the adverse impact of SD; specifically, those who are more depressed showed less trust after a night of sleep loss. However, this moderation effect was not detected using a within-subjects study design. Moreover, the 24-h SD only had a marginally significant effect on resting-state EEG indices in Study 1 and had no significant effect on rational decision-making in both studies. In contrast to previous studies adopting longer durations of SD, our limited significant findings suggest that the social brain may be relatively resilient to the effects of one night of SD, at least in a well-controlled laboratory setting. Future studies may compare different durations of SD and the potential moderating effects of individual differences variables, such as circadian preference, neuroticism, beliefs, and values on the relationship between SD and social decision-making behaviors. All rights reserved.
Study 1 examined the effect of one night of sleep deprivation on social decision-making using a between-subjects design. Forty-three healthy participants were randomly assigned to the sleep deprivation (SD) or sleep control (SC) group. After a week of habitual sleep at their own residences, participants in the SD group stayed awake in the laboratory for one night, while those in the SC group slept normally at home. In the morning after the sleep condition (SD/SC), all the participants underwent an 8-minute resting-state EEG recording and completed tasks related to sleepiness, vigilance and social decision-making. The following two EEG indices related to the emotional regulatory and cognitive process were calculated: frontal alpha asymmetry (the frontal alpha power difference between the right and left hemispheres) and the frontal theta/beta ratio (the power ratio of theta and beta bands over the frontal regions). The results showed marginal significance in the left-lateralized frontal alpha power following SD, suggesting a trend of poorer emotional regulation ability after sleep loss. However, there was no significant difference in the frontal theta/beta ratio between the SD and SC groups. Moreover, the effect of SD on trust was moderated by depressive symptoms. Compared to the controls, participants with a higher level of depressive symptoms showed fewer trusting behaviors after SD, while participants with a lower level of depressive symptoms showed more trusting behavior after SD. However, there was no significant difference in rational decision-making performance between the SD and SC groups.
Considering individual differences in vulnerability to SD, Study 2 was conducted to examine the effect of one night of SD on social decision-making using a within-subjects design. Forty-eight participants completed a counterbalanced repeated-measures study design involving a night of SD and a night of normal sleep (NS), 7 days apart in a counterbalanced order. The participants completed an 8-minute resting-state EEG recording and measures of sleepiness, vigilance and social decision-making after each
sleep condition (SD/NS). Contrary to the prediction, the trend of significant left-lateralized frontal alpha power after SD and the interaction effect between SD and depressive symptoms on trust found in Study 1 were not detected in Study 2, which showed no other significant effects, suggesting that 24 h of SD may not have robust effects on resting-state EEG indices and social decision-making.
Overall, this study provides the first evidence of the moderation effect of depressive symptoms on the relationship between SD and trust. The results show that people who have a higher level of depressive symptoms are more vulnerable to the adverse impact of SD; specifically, those who are more depressed showed less trust after a night of sleep loss. However, this moderation effect was not detected using a within-subjects study design. Moreover, the 24-h SD only had a marginally significant effect on resting-state EEG indices in Study 1 and had no significant effect on rational decision-making in both studies. In contrast to previous studies adopting longer durations of SD, our limited significant findings suggest that the social brain may be relatively resilient to the effects of one night of SD, at least in a well-controlled laboratory setting. Future studies may compare different durations of SD and the potential moderating effects of individual differences variables, such as circadian preference, neuroticism, beliefs, and values on the relationship between SD and social decision-making behaviors. All rights reserved.
| Original language | English |
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| Qualification | Doctor of Philosophy |
| Awarding Institution |
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| Supervisors/Advisors |
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| Publication status | Published - 2020 |
Keywords
- Sleep deprivation
- Resting-state EEG
- Social decision-making
- Young adults
- Theses and Dissertations
- Thesis (Ph.D.)--The Education University of Hong Kong, 2020.
