Recent studies of sleep

This is a longer than usual post because I am presenting four recent studies of sleep. First,

Palmer et al. (2023) published “Sleep Loss and Emotion: A systematic review and meta-analysis of over 50 years of experimental research” in Psychological Bulletin. The first sentence had my attention:

In a largely sleep-deprived society, quantifying the effects of sleep loss on emotion is critical for promoting psychological health. This preregistered systematic review and meta-analysis quantified the effects of various forms of sleep loss on multiple aspects of emotional experiences. Eligible studies used experimental reductions of sleep via total sleep deprivation, partial sleep restriction, or sleep fragmentation in healthy populations to examine effects on positive affect, negative affect, general mood disturbances, emotional reactivity, anxiety symptoms, and/or depressive symptoms. In total, 1,338 effect sizes across 154 studies were included (N = 5,717; participant age range = 7–79 years). Random effects models were conducted, and all forms of sleep loss resulted in reduced positive affect, increased anxiety symptoms, and blunted arousal in response to emotional stimuli. Findings for negative affect, reports of emotional valence in response to emotional stimuli, and depressive symptoms were mixed and depended on the type of sleep loss. Nonlinear effects for the amount of sleep loss as well as differences based on the stage of sleep restricted (i.e., rapid eye movement sleep or slow-wave sleep) were also detected. This study represents the most comprehensive quantitative synthesis of experimental sleep and emotion research to date and provides strong evidence that periods of extended wakefulness, shortened sleep duration, and/or nighttime awakenings adversely influence human emotional functioning. 

This study synthesizes more than 50 years of experimental research to reveal the multiple ways loss of sleep undermines human emotional functioning and increases risk for psychiatric disorders. Industries and sectors prone to sleep loss (e.g., first responders, pilots, truck drivers) should develop and adopt policies that prioritize sleep to mitigate against the risks to daytime function and well-being. 

So, it’s pretty clear that we should pay more attention to disruptions of sleep. Next, Chen, Benner & Kim (2023) published “Peer-Based Discrimination and Adolescent Emotional and Sleep Health: A daily examination of direct and buffering associations” in Child Development. Here’s the abstract:

Using 10-day daily diary data collected in 2019 from 10th grade students in southern U.S. (N = 161, 57% Latina/x/o, 21% Biracial, 10% Asian, 9% White, 4% Black; 55% female, Mage = 15.51), this study examined various forms of peer-based discrimination in adolescents’ everyday lives. Results showed that personally experienced discrimination, peer racial teasing, and vicarious discrimination were frequent and impactful events. Results also provided strong evidence for the protective role of psychological resilience and some evidence for the protective-reactive roles of peer support and school climate in moderating the link between peer-based discrimination and daily well-being. The findings highlight the necessity to eliminate peer-based discrimination and shed light on interventions to reduce the harmful effects of peer-based discrimination on adolescents’ daily well-being.

These findings are not surprising but illustrate again the importance of collecting information about sleep quality. The next study makes this point even clearer. Bregman-Hai & Soffer-Dudek (2023) published “Posttraumatic Symptoms and Poor Sleep are Independent Pathways to Agency disruptions and Dissociation: A longitudinal study with objective sleep assessment” in Journal of Psychopathology and Clinical Science. Here are the edited abstract and impact statements:

Dissociation and diminished sense of agency are experiential distortions of disintegration in the perception of self and action. Although one is often implied in the other, they are seldom studied together. Assessing their relationship and shared influences may allow for a more comprehensive and nuanced understanding of dissociative experiences. We aimed to examine their temporal (concurrent or directional) co-occurrence, and to elucidate their etiology, focusing on posttraumatic symptoms (PTS), poor sleep, and their hypothesized joint effect. N = 113 adults oversampled for the existence of trauma exposure history reported PTS and then, for a week, wore an actigraphic sleep monitor, reported subjective sleep quality each morning, and reported state dissociation (depersonalization, derealization, and absorption) and sense of agency four times each day. Data were analyzed using multilevel linear modeling. Higher state dissociation correlated with diminished state sense of agency, but only contemporaneously, not directionally. Both hypothesized etiological factors, namely, PTS (especially complex) and poor sleep (objective and subjective) predicted state dissociation and diminished state sense of agency, but psychological distress seemed to overshadow these main effects. However, robust interactive effects suggested that poor sleep predicted dissociation and disruptions in the sense of agency only among individuals with low PTS. These findings suggest that PTS and poor sleep quality are separate paths to dissociation and impaired sense of agency. 

There is some controversy over the centrality of trauma exposure in the etiology of a range of dissociative experiences, and it has been suggested that sleep-related factors may account for the association between trauma and dissociation. The current study suggests that posttraumatic symptoms and sleep disturbances are two different pathways to dissociative experiences, as objectively assessed sleep quality predicted dissociation mainly among individuals who were low in posttraumatic symptoms. 

This is not a huge sample but a cleverly designed study. While the simple hypothesis is not confirmed, the fact that poor sleep quality can be a path to dissociation and an impaired sense of agency is intriguing. Finally, Yau, et al. (2024) published “A Group-Based Transdiagnostic Sleep and Circadian Treatment for Major Depressive Disorder: A randomized controlled trial” in Journal of Consulting and Clinical Psychology.  Here are the edited abstract and impact statements:

Sleep and circadian disturbance is highly comorbid with a range of psychological disorders, especially major depressive disorder (MDD). In view of the complexity of sleep and circadian problems in MDD, this study aimed to evaluate the efficacy of a group-based transdiagnostic intervention for sleep and circadian dysfunction (TranS-C) for improving depressive symptoms and sleep and circadian functions. One hundred fifty-two adults diagnosed with comorbid MDD and sleep and circadian dysfunctions were randomized into TranS-C group treatment (TranS-C; n = 77) or care as usual (CAU; n = 75) control group. The TranS-C group received six weekly 2-hr group sessions of TranS-C, whereas the CAU group continued to receive usual care. Assessments were at baseline, immediate (Week 7), and 12-week (Week 19) posttreatment. Primary and secondary outcomes included depression, anxiety, sleep disturbances, fatigue, quality of life, and functional impairment. The TranS-C group showed significant improvement in depressive symptoms, insomnia severity, sleep disturbances, sleep-related impairment, fatigue, anxiety symptoms, quality of life, and sleep diary-derived parameters relative to the CAU group at immediate posttreatment. These treatment gains remained significant at 12-week follow-up. Significant improvement in functional impairment was also noted at 12-week follow-up. TranS-C was efficacious and acceptable in alleviating depressive symptoms and sleep and circadian disruptions in adults with MDD. The group format appears to be a low-cost, widely disseminable option to deliver TranS-C. Further research on TranS-C to examine its benefits on other psychiatric disorders is warranted. This was the first study to demonstrate the efficacy and acceptability of the group-based transdiagnostic intervention for sleep and circadian dysfunction (TranS-C) for improving comorbid depressive symptoms and sleep and circadian functions in adults with major depressive disorder (MDD). The TranS-C may be a suitable option to address more complex sleep disturbance profiles associated with MDD. 

I like to end on a positive note and this is a nicely designed study with powerful results. There is additional information about TranS-C in relation to studies of youth and other samples.