Sleep, Socioemotional Functioning, and Symptom Experience: An Experimental Sleep Restriction Study

Introduction and Context 

Concussions are very common in sport (Daugherty et al., 2020). As such, accurate assessment of concussion is imperative for safe participation in sport at all levels. A major domain of assessment is self-report symptoms (Patricios et al., 2023). It is well-known that concussion-like symptoms (CLS) are common both after concussion and in healthy athletes at baseline. Concussion symptoms should recover quickly and completely after concussion, but they persist in some athletes. There is evidence that these persistent symptoms after concussion can lead to feelings of loneliness, social isolation, and lack of emotional support (Choudhury et al., 2020). The factors predisposing, precipitating, and perpetuating concussion symptoms are various and include subjective and objective sleep disturbance. Similarly, sleep is known to be associated with social functioning (Gordon et al., 2017). However, little is known about the mechanism of these relationships. The present study aimed to examine the role of various facets of emotional functioning in the relation between the above-mentioned variables.  

Methods 

This was a two-part study. The first study used retrospective data from 266 healthy undergraduate students. For study 1, the relationship between sleep (subjective sleep disturbance [SSD] and free-living sleep duration) and concussion-like symptom reporting was examined. The second study was a mixed within- and between-subjects study using an experimental sleep restriction (ESR) paradigm. The relationship between experimentally restricted sleep (EMS) and concussion-like symptom reporting and EMS and social variables (loneliness, social isolation, and emotional support) was examined in 44 healthy undergraduate students. Their concussion-like symptoms and social functioning were measured at four timepoints (five days before ESR, the day before ESR, the day after ESR, and the day after a night of normal sleep). Sleep debt accumulation was monitored using Fitbit devices in the five nights preceding the experimental sleep restriction. In both studies, multiple facets of emotional functioning were examined as mediators in these relationships.  

Key Findings and Implications 

Study 1: This study demonstrated associations between emotional functioning and CLS, SSD and CLS, and free-living sleep duration and CLS using correlational and mean comparison procedures. Those with SSD or short duration sleep (defined as <5.5 hours the previous night) reported more CLS than those without sleep disturbance or adequate sleep. Contrary to hypotheses, there was no interaction between sleep group (short vs. adequate sleep) and sex. The interaction between subjective sleep disturbance (present vs. absent) and sex was also non-significant. Emotional distress mediated the relation between SSD and CLS, but not the relation between free-living sleep duration and CLS.  

Study 2: This study showed similar associations between experimentally manipulated sleep and CLS reporting with large mean differences after ESR (Mean of experimental group = 37.59, Mean of control group = 11.05). There were no differences in social functioning as a result of ESR. Total emotional distress, depression, anxiety, stress, and negative affect mediated the relation between EMS and concussion-like symptom reporting. There was an indirect effect of total emotional distress, depression, anxiety, stress, and negative affect in the relationship between EMS and social variables. These emotional variables also mediated the relation between SSD and the social variables. Positive affect did not mediate any relationship. 

Implications: Several facets of emotional functioning mediate the relation between both SSD and EMS duration and concussion-like symptom reporting. This has many implications for safe participation in sports due to the high prevalence of concussion. For example, if athletes report many symptoms at baseline concussion assessment, intervention for sleep and/or emotional functioning can ameliorate these symptoms. This is particularly important because these baseline measures of symptoms are commonly used as the metric of recovery. If inaccurate baseline data (due to poor sleep or emotional functioning) are used, this can result in potentially harmful decision making for safe return to play. Similarly, after concussion, if athletes report many symptoms or their symptoms do not recover within the expected timeframe, interventions for sleep or emotional functioning can help athletes return to play in a safe manner. This may be especially helpful if athletes have had previous unsuccessful intervention for either sleep or emotional issues, because intervention can then be targeted at the other variable with similar effects on their concussion-like symptoms. Successful interventions for these sleep and emotional disturbance will lead to more accurate measurement of symptomatology, which will facilitate quicker and safer return to play and participation in sport for athletes who suffer concussion. As well, improvement of symptoms at baseline may improve athlete performance. Furthermore, if they experience persistent symptoms after concussion, which can lead to loneliness, the results of this study implicate sleep and/or emotional interventions to ameliorate their social functioning.  

Strengths and Limitations 

This study had many strengths, including assessment of multiple facets of sleep functioning (SSD, free-living sleep duration, and experimentally manipulated sleep duration), examination of multiple facets of emotional functioning, and tight control of sleep-related variables in the second study. Limitations include the demographics of the samples (young adult, primarily Caucasian, primarily English-speaking, university students), collection of data at different times in the academic semesters (and thus, different levels of stress related to academic tasks), collection of data during the COVID-19 pandemic, and over-sensitivity (and thus lower specificity) of Fitbit devices to sleep. 

Conclusions and Next Steps 

Sleep dysfunction is associated with increased concussion-like symptom reporting and social functioning. Emotional functioning mediates this relationship. These findings indicate that sleep and emotional functioning are imperative to include in assessments of concussion to ensure quick and safe return to play after concussion, and ensuring athletes have minimal symptom burden at baseline. If symptoms persist longer than the typical recovery time, athletes can feel isolated. The findings of the present study indicate that interventions aimed at sleep and emotional functioning can help to ameliorate these feelings of loneliness and social isolation as well to enhance the well-being of athletes and help them to feel ready to return to play. Future studies should examine this question with several nights of sleep restriction (as opposed to one night like in the current study) in more representative samples. Furthermore, this research should be replicated in a sample of athletes.