Sleep Loss and Emotion: A Systematic Review and Meta-Analysis

Sleep is a fundamental need, while emotions are ubiquitous experiences affecting health, motivation, cognition, relationships, and more (Engen & Anderson, 2018; Ferrer & Mendes, 2018).

Considerable evidence shows poor sleep catalyzes emotional problems across lifespans (Goldstein & Walker, 2014; Gregory et al., 2009).

For example, over 30% of U.S. adults and up to 90% of teenagers fail to get recommended sleep (Basch et al., 2014; Liu et al., 2016). Mobile technology data indicate similarly insufficient sleep worldwide (Walch et al., 2016).

Given sleep’s impact on emotional functioning, these trends hold substantial public health and policy implications regarding matters such as school start times, work schedules, and military operations.

Palmer, C. A., Bower, J. L., Cho, K. W., Clementi, M. A., Lau, S., Oosterhoff, B., & Alfano, C. A. (2023). Sleep loss and emotion: A systematic review and meta-analysis of over 50 years of experimental research. Psychological Bulletin. Advance online publication. https://doi.org/10.1037/bul0000410

Key Points

1. All forms of sleep loss (total sleep deprivation, partial sleep restriction, sleep fragmentation) resulted in reduced positive affect.
2. Sleep loss increased anxiety symptoms and blunted emotional arousal to stimuli.
3. Effects on negative affect, depressive symptoms, and emotional valence were mixed and depended on the type of sleep loss.
4. The effects of sleep loss on emotion peaked at certain levels of wakefulness or restricted sleep duration.
5. Loss of REM sleep resulted in greater unpleasantness ratings compared to loss of slow-wave sleep.

Rationale

Sleep plays a critical role in emotional functioning, yet a large portion of the population fails to get adequate sleep (Hafner et al., 2017; Liu et al., 2016).

Quantifying how sleep loss alters emotions is critical for elucidating affective disease pathways and guiding regulations promoting healthy sleep duration.

Inadequate sleep appears to be a salient risk factor for psychiatric disorders by disrupting emotional systems. Thus, understanding the precise emotional consequences of sleep loss has immediate, far-reaching relevance (Goldstein & Walker, 2014; Triantafillou et al., 2019).

Method

This meta-analysis included 154 experimental studies (N = 5,717) manipulating healthy participants’ sleep via total sleep deprivation (TSD), partial sleep restriction (PSR), or sleep fragmentation (SF).

Outcomes were positive affect, negative affect, mood disturbances, emotional valence/arousal, anxiety, and depression.

Inclusion criteria

Participants:

• Did not have any psychiatric, sleep disorders, or medical conditions known to impact sleep or emotional functioning. Samples at high risk for circadian disruption were excluded (e.g., pilots).
• No restrictions on age of participants.

Sleep Manipulation:

• Experimentally manipulated reductions in nighttime sleep, including total sleep deprivation (TSD), partial sleep restriction (PSR), or sleep fragmentation (SF) over 1+ nights.
• Did not include studies manipulating daytime naps, forced desynchrony, phase shift protocols, sleep extension, or recovery sleep.

Comparison Condition:

• An adequate control group with typical/healthy sleep was used for comparison.

Dependent Variables:

• Assessed emotional outcomes after sleep manipulation, including positive/negative affect, mood disturbances, emotional valence/arousal, anxiety symptoms, or depression symptoms.
• Did not include behavioral or physiological indicators of emotional functioning or neuroimaging variables.

Excluded Other Interventions:

• No other interventions occurred prior to emotional assessment that impacted sleep or emotion (e.g. intense exercise, extreme training, work simulation, emotion extinction paradigms, pharmacological agents).

Sample

Participants were aged 7-79 years old (M = 23.66 years) and 50.14% female. Most studies used young adult samples.

Statistical Measures

Standardized mean differences (Hedges’ g) were calculated for each effect. Multilevel meta-analyses estimated overall effects and moderators.

Results

In summary, inadequate sleep reliably reduced positive emotions and increased anxiety. Findings were more variable for negative affect, mood disturbances not characterized by valence, depressive symptoms, and facets of emotion reactivity like arousal.

Emotion Reactivity

• Sleep deprivation and sleep fragmentation blunted emotional arousal to stimuli.
• Sleep restriction increased unpleasantness ratings to emotional stimuli.
• Changes in subjective valence ratings were insignificant or mixed across sleep loss types.

Positive Affect, Negative Affect, & Mood Disturbances

• All types of sleep loss reduced positive affect. These effects were the most consistent and largest in size.
• Findings for negative affect were mixed – it increased somewhat with total sleep deprivation and restriction but changes were small.
• General mood disturbances increased under total sleep deprivation and restriction but not sleep fragmentation.

Anxiety and Depressive Symptoms

• Sleep loss increased anxiety symptoms across all manipulation types. Effects were stronger in youth.
• Changes in depressive symptoms were mixed – partial sleep restriction increased them but total deprivation showed insignificant changes.

Here are the results summarized based on the study’s hypotheses:

The hypothesis that sleep loss would negatively impact all emotional constructs was supported, but other specific hypotheses regarding dose-response effects, REM vs SWS deprivation, and individual differences were only partially supported or remained inconclusive.

Insight

This meta-analysis shows sleep deprivation consistently reduces positive emotions. All types of sleep loss studied, including truncating time in bed and fragmenting sleep, blunted positive affect.

These effects were more reliable than impacts on negative moods. Emotional numbing also occurred – sleep deficient people had muted arousal to emotional stimuli. Anxiety symptoms rose with inadequate rest regardless of manipulation type.

Changes in general mood disturbances, unpleasantness, and depression were more inconsistent, sometimes increasing under certain sleep loss conditions but not others. Effects depended on factors like the amount of REM versus slow-wave sleep loss (SWS).

In youth, emotional impacts were typically magnified. Taken together, findings cement healthy sleep as crucial for emotional health. With chronic sleep deficiency pervasive in modern society, these shifts likely promote psychiatric problems.

Safeguarding sufficient sleep opportunities through health policies and education is critical, given its clear role in sustaining emotional well-being.

Strengths

• Included multiple types of sleep loss and emotion constructs using clear definitions
• Assessed nonlinearity of sleep dose effects
• Compared REM versus slow-wave sleep loss (SWS)
• Examined age/sex as moderators
• Used rigorous meta-analytic techniques

Limitations

• Studies could not fully mask conditions
• Primarily focused on young adults
• Few studies reduced REM or SWS sleep specifically
• Physiological emotional indices were excluded

Implications

These findings firmly establish sleep as a determinant of daily emotional functioning. Shortened or disrupted sleep schedules common in modern society may promote psychiatric disorders by altering emotion systems.

Policies should better promote healthy sleep duration to protect mental health.

They also underscore the need for health policies regulating work hours and school schedules to promote sufficient sleep opportunities for mental health. Understanding these emotional pathways is key for elucidating sleep’s role in psychiatric diseases.

References

Basch, C. E., Basch, C. H., Ruggles, K. V., & Rajan, S. (2014). Prevalence of sleep duration on an average school night among 4 nationally representative successive samples of American high school students, 2007–2013. Preventing chronic disease, 11.

Engen, H. G., & Anderson, M. C. (2018). Memory control: A fundamental mechanism of emotion regulation. Trends in cognitive sciences, 22(11), 982-995.

Goldstein, A. N., & Walker, M. P. (2014). The role of sleep in emotional brain function. Annual review of clinical psychology, 10, 679-708.

Hafner, M., Stepanek, M., Taylor, J., Troxel, W. M., & van Stolk, C. (2017). Why sleep matters-the economic costs of insufficient sleep: a cross-country comparative analysis. Rand health quarterly, 6(4).

Liu, Y., Wheaton, A. G., Chapman, D. P., & Croft, J. B. (2016). Sleep duration and chronic diseases among US adults age 45 years and older: evidence from the 2010 Behavioral Risk Factor Surveillance System. Sleep, 39(8), 1421-1427.

Triantafillou, S., Saeb, S., Lattie, E. G., Mohr, D. C., & Kording, K. P. (2019). Relationship between sleep quality and mood: ecological momentary assessment study. JMIR mental health, 6(3), e12613.

Walch, O. J., Cochran, A., & Forger, D. B. (2016). A global quantification of “normal” sleep schedules using smartphone data. Science advances, 2(5), e1501705.

Keep Learning

1. How might these findings explain the high comorbidity between sleep disturbances and psychiatric disorders?
2. Can these emotional changes following acute sleep loss help explain the craving for unhealthy foods often reported when sleep deprived?
3. What might be some confounding variables that this meta-analysis was unable to account for?
4. What are some potential societal or occupational situations where these findings could be directly applied?