Research Projects
We studied the complex functions of sleep in making risky decisions, as well as the moderators and mediators of the connections in young people. Using both subjective and objective measurements of at-home nightime sleep and in-lab daytime sleep, we found that people with subjective sleep needs and long-term sleep deprivation exhibited greater impulsivity in risk-related decision-making. Naps were shown to be an effective way to reduce impulsivity in risk-related decision-making as well as to improve vigilance, planning, and other cognitive functions. The amount of sleep spindles (a specific wave-form in stage 2 sleep) measured by polysomography (PSG) during naps was linked to less impulsive risk-related decision-making. Our study highlights the impact of sleep in higher congitive functions like risk-related decision-making and planning, beyond the basic functions of vigilance and reaction time.
This project investigated the effect of an additional sleep opportunity in emotional processing, a function which underlies various physical, psychological and social/occupational functioning. A 90-min daytime nap benefits how we felt, recall, and control our responses in face of emotional information, regardless of whether we restrict our sleep habitually, and without negative impact on subsequent nighttime sleep condition.
Sleep on it: Effects of daytime naps and nighttime sleep on emotional processing in college students
(SNEF)
General Research Fund,
Research Grants Council, HKSAR
Project number: 18619616
The Impact of Sleep Deprivation on Emotional Functioning and Its Electroencephalographic (EEG) Correlates
(SDEF)
General Research Fund,
Research Grants Council, HKSAR
Project number: 18611717
Sleep loss has become a prevalent problem around the world. This project aimed to examine the impact of a night of sleep loss on emotional functioning and the neural underpinnings. We found that sleep deprivation compromised 1) emotion-related neural activities as indexed by resting-state EEG markers; 2) emotional regulation as indexed by behaviroal task and neural correlates. Characterizing the emotional consequences of sleep loss is pivotal to understanding disorders involving sleep disturbances and mood symptoms and crucial to informing public health policies.
Sleep disturbance is associated with the onset and maintenance of depression; the normal sleep architecture is also found to be altered in individuals with depression. This project aimed to experimentally investigate whether a period of daytime sleep changed the emotional processing differently in depressed patients, as compared to healthy controls. We discovered that sleep-related perceptual changes of emotional expressions were observed exclusively in individuals with depression after a REM-containing daytime nap. This project serves as an important step toward understanding the role of sleep in emotional processing in depression, and providing further basis for the transdiagnostic treatment of sleep in individuals with different psychopathologies manifesting cognitive and affective deficits.
Bereavement is a highly negative and yet unavoidable life event for most people. Religious conversion is less frequent. It is a sharp and rapid change from having no religion to having a religion, or from being affiliated with one religion to being affiliated with another. Contrary to common beliefs, bereavement alters some but not all personality and values. Emotional stability increases for those who are older and have little psychological symptoms initially. It declines for those who are younger and psychologically less well. Whether the self-direction value would be weakened depends on age and the use of religious coping. Bereavement has negative effect on wellbeing two years later. The stronger is the perceived severity of the loss, the greater is the negative impact. The harmful effects of holding a strong belief in fate control are aggravated by bereavement. People who undergo religious conversion are transformed in forgivingness, symptoms of stress and anxiety, as well as several personal values, including benevolence, achievement, and conformity. The current project is important as it shows that personality and values are fairly stable, and yet life events can change some. It provides the knowledge base for practitioners to help people thrive amidst their life circumstances.
In a study of 987 Chinese working adults we found moderate correlations among sleep quality, depressive mood, and optimism. There is a bidirectional causality between optimism and sleep. Depressive mood fully explained the influence of optimism on sleep quality, and partially explained the influence of sleep quality on optimism. In short, optimism improves sleep; poor sleep makes a pessimist.
In another study of 1,684 college students, we found moderate correlations among sleep quality, depressive mood, stress symptoms, anxiety symptoms, and optimism. There was also a bidirectional effect between optimism and sleep quality. Anxiety and stress symptoms partially explained the influence of optimism on sleep quality, while depressive mood partially explained the influence of sleep quality on optimism. Moreover, poor sleep resulted in depressive mood and pessimism in non-morning persons only. In contrast, the effects of optimism on sleep quality existed regardless of circadian preference. Taken together, people who are pessimistic have more anxious mood and stress symptoms, which adversely affect sleep while morningness seems to have a specific protective effect countering the potential damage poor sleep has on optimism.
This project revealed the associations between sleep and personality traits and beliefs, namely neuroticism, positive worldview and social cynicism. First, there is a bidirectional relationship between sleeping well and an optimistic view of life. Second, a forgiving attitude contributes to one’s emotional stability, which then leads to better sleep. Third, negative worldview leads to bitterness and unforgiveness, and unwillingness to forgive causes interpersonal conflict. Last, there is a correlation between sleep disturbance and unforgivingness.
Sleep disturbance is a pandemic affecting almost half of the world’s population. Sleep has been proposed to be a core transdiagnostic process that underlies various psychological disorders. Beyond the disease model, evidence also suggests that sleep variables are associated with a wide array of human functioning, from physical health, neurocognitive affective functions, social relationships, to personality formation and character development. Given the prevalence and pervasiveness of sleep problems, it is of pivotal importance to investigate their long-term consequences. Previous studies reported the effects of sleep quality at a particular time point or its average across multiple time points; this proposal distinguishes itself by studying the effects of the path of change in sleep quality over time, namely the sleep quality trajectory, which is more meaningful and powerful as it captures intraindividual longitudinal development. We focused on emerging adulthood for the established significance of this developmental period for human growth and flourishing. To break through the constraints of previous research, we shall capitalize on an existing eight-year dataset, and bring it up to the next level to by collecting another wave of data including objective measures of sleep and a comprehensive set of flourishing outcome variables, with some of which being objectively-measured. This project will result in a 10-year dataset of a theoretically-driven and empirically-based list of biopsychosocial-spiritual variables, with the key variables of sleep and some flourishing outcomes measured both by a longitudinal survey as well as in-lab objective tests. This novel design will enable us to investigate the flourishing outcomes and psychosocial determinants of sleep trajectory in the critical period of emerging adulthood in a methodologically rigorous manner with potential for high theoretical and clinical significance.
This project tested 188 young adults for two time-points with 12 months apart. Self-reported poor sleep quality and insomnia symptoms prospectively predicted self-reported and clinician-diagnosed anxiety and depression at follow-up. Sleep problems’ effects on depression were found to be explained by attention-bias. In other words, young adults may become depressed due to how to pay attention to emotional information, which in turn is rooted in poor sleep. Given that sleep problems have been shown to be readily treatable or manageable by psychological or pharmacological intervention at a rather lower intensity level than depression and anxiety, our study provides a solid rationale for policy makers and health professionals to direct more attention to sleep problems in the prevention and treatment of anxiety and depression.