About

Dr. Susan Charles is a Professor and Principal Investigator at the Emotion Research Lab. She earned her Ph.D. from the University of Southern California. Dr. Charles' research focuses on emotional processes across the adult life span, with particular interest in how subjective experience varies throughout the life course. She investigates how differences in subjective experience may be related to differences in cognitive processes. Additionally, Dr. Charles explores the interplay between health and emotion, examining the relationship between physical health factors—including both health behavior and health status—and emotional processes. Her work also considers how these relationships may vary as a function of age.

Research topics

• Psychology
• Medicine
• Gerontology
• Clinical psychology
• Computer Science
• Developmental psychology
• Artificial Intelligence
• Political Science
• Psychiatry
• Sociology
• Cognitive psychology
• Business
• Process management
• Virology
• Medical education
• Social psychology
• Demography
• Human–computer interaction

Selected publications

• Computing the Dynamic Range of Diurnal Cortisol: Approaches, Implications, and Statistical Considerations

  2025-07-25

  preprintOpen access

  Recent research suggests that the dynamic range of diurnal cortisol (or cortisol dynamic range, CDR) serves as a feasible proxy of hypothalamic pituitary adrenal axis (HPA-axis) regulation and an indicator of allostatic load. The CDR is a measure that captures the range of cortisol output throughout the waking day, spanning from the lowest to highest estimated value. A key advantage of using the CDR compared to other common cortisol metrics is the incorporation of multiple assessments across several days into a single estimate that more reliably captures dynamic homeostatic processes. Calculating the CDR may benefit researchers who are seeking to assess a single marker of dynamic HPA-axis functioning. However, the CDR is novel and somewhat complex; thus, the goal of the current paper is to provide a tutorial for calculating the CDR. We present three different approaches to calculating the CDR. For each approach, we outline several critical statistical and conceptual advantages and limitations, and end by presenting analytic examples using publicly available data and including R code. The current paper may serve as a resource for researchers planning studies or evaluating data involving the CDR.

  PublisherDOI

• The National Study of Daily Experiences: Protocol for Assessments of Daily Stress, Well-Being, Health, and Salivary Biomarkers in a Longitudinal Cohort (Preprint)

  2025-05-07

  preprint

  <sec> <title>BACKGROUND</title> Modern psychology has long recognized that understanding human behavior requires knowledge about a person’s current context, which is often examined through daily diary studies. These studies offer ecologically valid insights into how everyday experiences—particularly stressors—affect health and well-being. The National Study of Daily Experiences (NSDE) addresses a critical gap by applying this approach in a large, longitudinal, and publicly accessible study that captures daily life across adulthood. </sec> <sec> <title>OBJECTIVE</title> The NSDE is the largest and longest-running publicly accessible daily diary study in the United States. The purpose of this paper is to provide a guide for researchers interested in initiating similar naturalistic studies and to facilitate research using the existing NSDE data. </sec> <sec> <title>METHODS</title> The NSDE includes 3510 adults (aged 24-97 years), yielding over 42,000 days of information to capture how daily life changes with age, over time, and across different cohorts, and how these daily experiences predict later health and well-being. This intensive longitudinal dataset includes an 8-day daily diary collected via phone survey, spans more than 20 years, and consists of 2 longitudinal datasets. During the daily phone interviews, participants provide reports of their experiences regarding daily events, including their stressors (Daily Inventory of Stressful Events), as well as their physical health indices, emotional experiences, and cognitive health. In addition, saliva is collected concurrently with days 2-5 of the daily phone interviews (4 collections per day for 4 consecutive days) and is used to measure biomarkers such as cortisol and alpha amylase. </sec> <sec> <title>RESULTS</title> Recruitment began in 1995, with data collection occurring every 9-10 years. The most recent data collection is ongoing through 2027. All NSDE data are housed under the Midlife in the United States (MIDUS) study umbrella, with archived and updated datasets made available to the public on the online portal, MIDUS Colectica. </sec> <sec> <title>CONCLUSIONS</title> Results from the NSDE have refined our understanding of daily stress processes. The study’s timescale has provided insight into daily life for hundreds of studies, yet much more can be learned from using these data. Microlongitudinal measures and combinations of factors provide for new avenues of research and promise for better understanding of health and aging. Moreover, NSDE data can be combined with datasets from neuroscience, biomarker, and macrolongitudinal subprojects from MIDUS to examine health-related processes. In addition to offering information on how to use the NSDE, this protocol serves as a resource for secondary data analyses and an outline for investigators wishing to replicate an intensive assessment design to other populations and research questions to continue to refine our understanding of how daily stress processes influence health and well-being. </sec> <sec> <title>CLINICALTRIAL</title> <p/> </sec> <sec> <title>INTERNATIONAL REGISTERED REPORT</title> DERR1-10.2196/76453 </sec>

  PublisherDOI

• The advantages of seeing the silver lining: how valuing emotions moderates the link between ambivalent ties and daily health

  The Journals of Gerontology Series B · 2025-07-02

  articleOpen access

  OBJECTIVES: Relationships that elicit both positive and negative emotions, known as ambivalent ties, are often linked to adverse health outcomes in later life. Their negative health impacts, however, may depend on how older adults appraise different emotional experiences (e.g., viewing relationship "ups and downs" as useful or meaningful). This study examined whether bivalent affect valuation (BAV; the extent to which people appraise both positive and negative emotions as valuable) moderates the link between ambivalent ties and health-related limitations in daily activities. METHODS: Community-dwelling older adults (N = 250, older adults aged 65-89years) completed an in-person interview assessing their social ties and sociodemographic factors, followed by a self-administered questionnaire assessing their valuation of positive and negative emotions, and 5-6 days of momentary assessments examining their social encounters (every 3 h) and health-related limitations each day (at bedtime). RESULTS: Overall, greater exposure to ambivalent ties was associated with more health-related limitations across all days in the study period. Among older adults with greater BAV, however, greater exposure to ambivalent ties on a given day was associated with fewer health-related limitations that day compared to days with less exposure to ambivalent ties. Sensitivity analyses revealed that this effect was likely due to valuing negative affect, specifically. DISCUSSION: These findings highlight the importance of considering how older adults' valuation of their emotions, particularly their negative emotions, might influence the health-related toll of ambivalent ties.

  PublisherOA PDFDOI

• The National Study of Daily Experiences: Protocol for Assessments of Daily Stress, Well-Being, Health, and Salivary Biomarkers in a Longitudinal Cohort

  JMIR Research Protocols · 2025-08-31

  articleOpen access

  BACKGROUND: Modern psychology has long recognized that understanding human behavior requires knowledge about a person's current context, which is often examined through daily diary studies. These studies offer ecologically valid insights into how everyday experiences-particularly stressors-affect health and well-being. The National Study of Daily Experiences (NSDE) addresses a critical gap by applying this approach in a large, longitudinal, and publicly accessible study that captures daily life across adulthood. OBJECTIVE: The NSDE is the largest and longest-running publicly accessible daily diary study in the United States. The purpose of this paper is to provide a guide for researchers interested in initiating similar naturalistic studies and to facilitate research using the existing NSDE data. METHODS: The NSDE includes 3510 adults (aged 24-97 years), yielding over 42,000 days of information to capture how daily life changes with age, over time, and across different cohorts, and how these daily experiences predict later health and well-being. This intensive longitudinal dataset includes an 8-day daily diary collected via phone survey, spans more than 20 years, and consists of 2 longitudinal datasets. During the daily phone interviews, participants provide reports of their experiences regarding daily events, including their stressors (Daily Inventory of Stressful Events), as well as their physical health indices, emotional experiences, and cognitive health. In addition, saliva is collected concurrently with days 2-5 of the daily phone interviews (4 collections per day for 4 consecutive days) and is used to measure biomarkers such as cortisol and alpha amylase. RESULTS: Recruitment began in 1995, with data collection occurring every 9-10 years. The most recent data collection is ongoing through 2027. All NSDE data are housed under the Midlife in the United States (MIDUS) study umbrella, with archived and updated datasets made available to the public on the online portal, MIDUS Colectica. CONCLUSIONS: Results from the NSDE have refined our understanding of daily stress processes. The study's timescale has provided insight into daily life for hundreds of studies, yet much more can be learned from using these data. Microlongitudinal measures and combinations of factors provide for new avenues of research and promise for better understanding of health and aging. Moreover, NSDE data can be combined with datasets from neuroscience, biomarker, and macrolongitudinal subprojects from MIDUS to examine health-related processes. In addition to offering information on how to use the NSDE, this protocol serves as a resource for secondary data analyses and an outline for investigators wishing to replicate an intensive assessment design to other populations and research questions to continue to refine our understanding of how daily stress processes influence health and well-being. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/76453.

  PublisherDOI

• Computing the Dynamic Range of Diurnal Cortisol: Approaches, Implications, and Statistical Considerations

  2025-07-31

  preprintOpen access

  Recent research suggests that the dynamic range of diurnal cortisol (or cortisol dynamic range, CDR) serves as a feasible proxy of hypothalamic pituitary adrenal axis (HPA-axis) regulation and an indicator of allostatic load. The CDR is a measure that captures the range of cortisol output throughout the waking day, spanning from the lowest to highest estimated value. A key advantage of using the CDR compared to other common cortisol metrics is the incorporation of multiple assessments across several days into a single estimate that more reliably captures dynamic homeostatic processes. Calculating the CDR may benefit researchers who are seeking to assess a single marker of dynamic HPA-axis functioning. However, the CDR is novel and somewhat complex; thus, the goal of the current paper is to provide a tutorial for calculating the CDR. We present three different approaches to calculating the CDR. For each approach, we outline several critical statistical and conceptual advantages and limitations, and end by presenting analytic examples using publicly available data and including R code. The current paper may serve as a resource for researchers planning studies or evaluating data involving the CDR.

  PublisherOA PDFDOI

• Psychological distress across 2 years of the COVID‐19 pandemic differs by age and by race/ethnicity

  Journal of Traumatic Stress · 2025-06-11 · 1 citations

  articleOpen access

  The COVID-19 pandemic profoundly impacted mental health, with psychological distress varying across age and racial/ethnic groups. This study examined trajectories of five distress measures-symptoms of posttraumatic stress (PTS), anxiety, depression, anger, and somatization-over the first 2 years of the pandemic, adjusting for prepandemic mental health. Participants in a nationally representative, probability-based U.S. sample (N = 4,298, age range: 18-97 years) completed four online surveys from March 2020 to June 2022. Multilevel models revealed that symptom levels and changes over time varied by age group across outcomes. Across time, PTS and anxiety symptoms declined for most age groups at different rates, F(6, 85,660) = 6.21, p < .001. Younger adults initially reported higher PTS symptom levels at Wave 1, Bs = 0.10-0.14, p < .001, but levels converged across age groups by Wave 4. Rates of anxiety symptoms were similar across age groups at Wave 4 except for older adults, who reported significantly lower levels. Depressive symptoms and anger increased in the initial waves but declined by Wave 4, Bs = -0.25-0.02, p < .001. For all participants, somatization increased after Wave 1, B = -0.30, p < .001, and never returned to initial levels, B = -0.04, p < .001. Additionally, somatization was the only symptom with similar levels across age groups at each wave. Across race/ethnicity, Hispanic adults reported higher distress and less decline over time. Findings highlight distinct symptom trajectories across the pandemic, with generally lower distress levels among the oldest adults.

  PublisherOA PDFDOI

• Daily association between perceived control and resolution of daily stressors strengthens across a decade of adulthood

  Communications Psychology · 2025-08-27

  articleOpen access

  Greater perceived control is often associated with better responses to life's stressors. One reason for this link may be that greater perceived control is related to the ability to resolve these stressful experiences. Using longitudinal data from the National Study of Daily Experiences (N = 1766, Mage = 56.25, SD = 12.20, 57% women, 43% men), we examined associations between perceived control over daily stressors and the likelihood of stressor resolution, and how associations varied over a decade. In two waves conducted in ~2005 and ~2015, participants reported perceived control and resolution of their daily stressors across eight consecutive days. Generalized multilevel models adjusted for trends across days and waves, as well as number of stressors, gender, education, and race. People experiencing greater stressor control across the study days were more likely to report stressor resolution (OR = 1.92, 95%CI: 1.74-2.13, p < 0.001). Further, individuals were more likely to report stressor resolution on days when they reported greater control over their stressors than usual (OR = 1.66, 95%CI: 1.57-1.77, p < 0.001). This within-person association increased in magnitude across waves (OR = 1.21, 95%CI: 1.06-1.39, p < 0.01), resulting in a stronger association between stressor control and resolution when individuals were 10 years older (OR = 1.89, 95%CI: 1.69-2.12, p < 0.001). Results indicate perceived control is a psychosocial correlate of stressor resolution and an important appraisal resource for daily stress processes across the adult lifespan.

  PublisherOA PDFDOI

• Purpose in life mediates the relationship between social activity variety and depressive symptoms in Middle-aged and older U.S. adults

  Aging & Mental Health · 2025-09-08

  articleSenior author

  OBJECTIVES: Being socially integrated is vital to emotional well-being, partly because social connections provide purpose. Nevertheless, fewer have explored purpose in life as a potential mechanism linking social activity variety, one of the indicators of social integration, to mental health outcomes. This study examined purpose in life as a mediator in the relationship between earlier social activity variety and later depressive symptoms among U.S. adults aged 51 and above. METHOD: We ran autoregressive cross-lagged panel models using data from 4931 participants in the 2008, 2012 and 2016 waves of the Health and Retirement Study (HRS). Social activity variety, purpose in life, and depressive symptoms were measured at all three waves. RESULTS: Our findings reveal that higher levels of social activity variety at Wave 1 were related to increases in purpose in life from Wave 1 to Wave 2, which, in turn, was related to lower levels of depressive symptoms at Wave 3. CONCLUSIONS: These results suggest that purpose in life may serve as an important link between social activity variety and mental health outcomes in later life, offering new insights into how participation in a diverse range of social activities can reduce depressive symptoms through enhanced purpose in life.

  PublisherDOI

• MOMENTARY UNCONSTRUCTIVE REPETITIVE THINKING, WORKING MEMORY, AND AGE

  Innovation in Aging · 2024-12-01

  articleOpen accessSenior author

  Abstract Both trait and daily negative affect are often associated with lower performance on working memory tasks, perhaps because negative affect is often related to unconstructive repetitive thinking (URT) – negative ruminative thoughts about oneself or the environment. URT is posited to deplete attentional resources, resulting in downstream effects on cognition. Studies examining the effects of URT on cognitive performance often use laboratory-based study designs. This study aimed to investigate how reports of URT throughout the day are linked to scores on momentary cognitive tasks of verbal working memory. We hypothesized that reports of greater engagement in URT will be related to worse working memory, and that this association was related to age. Data from the Effects of Stress on Cognitive Aging, Physiology, and Emotion (ESCAPE) study included 263 community residents ranging from 25 to 65 years old (Mage = 46.5) completing five assessments throughout the day across 14 days. Contrary to our hypothesis, we found that greater URT was related to improved verbal working memory (γ =.005, SE =.001, p &amp;lt;.001). Higher momentary negative affect was related to poorer working memory, acting as a suppressor on the benefits of URT on working memory performance. This relationship between URT and verbal working memory remained significant across ages, but the relationship between levels of URT and working memory was strongest among younger adults.

  PublisherOA PDFDOI

• Changes in daily stress reactivity and changes in physical health across 18 years of adulthood

  Annals of Behavioral Medicine · 2024-12-03 · 6 citations

  articleOpen access

  BACKGROUND: Stress plays a pivotal role in physical health. Although many studies have linked stress reactivity (daily within-person associations between stress exposure and negative affect) to physical health outcomes, we know surprisingly little about how changes in stress reactivity are related to changes in physical health. PURPOSE: The current study examines how change in stress reactivity over 18 years is related to changes in functional health and chronic health conditions. METHODS: Three measurement bursts from the National Study of Daily Experiences (N = 2880; 55% female) each included daily measures of stressor exposure and negative affect across 8 consecutive days, yielding 33 944 days of data across 18 years of adulthood. At each wave, participants reported their functional health limitations (ie, basic activities of daily living [ADL] and instrumental activities of daily living [IADL]) and chronic health conditions. Multilevel structural equation models simultaneously modeled stress reactivity at Level 1, longitudinal changes in stress reactivity at Level 2, and the association between changes in stress reactivity and changes in functional limitations and chronic conditions at Level 3. RESULTS: Higher levels of stress reactivity at baseline were associated with more functional health limitations 18 years later (ADLs: Est. = 0.90, P = .001; IADLs: Est. = 1.78, P < .001). Furthermore, individuals who increased more in their stress reactivity across the 18-year period also showed greater increases in their functional health limitations (ADLs: Est. = 4.02, P = .017; IADLs: Est. = 5.74, P < .001) and chronic conditions (Est. = 11.17, P = .008). CONCLUSIONS: These findings highlight the strong connection between health and stress in daily life, and how they travel together across adulthood.

  PublisherOA PDFDOI

Recent grants

• NIH Grant R01AG023845

  NIH · $1.1M · 2011

• NIH Grant R01AG042431

  NIH · $298k · 2016

• NIH Grant R03AG019387

  NIH · $72k · 2002

Frequent coauthors

• David M. Almeida

  Pennsylvania State University

  59 shared

• Paul Das

  32 shared

• W. A. Armstrong

  32 shared

• David Cox

  32 shared

• H. Kaufmann

  Helmholtz Centre Potsdam - GFZ German Research Centre for Geosciences

  32 shared

• Jennifer R. Piazza

  California State University, Fullerton

  30 shared

• Karen L. Fingerman

  The University of Texas at Austin

  28 shared

• Gloria Luong

  21 shared

Labs

• Emotion Research LabPI

  1-2 sentence research focus

Education

• Ph.D.

  University of Southern California