The Connection Between Bereavement, Sleep, and Inflammation
By Ellen Feldman, MD
Altru Health System, Grand Forks, ND
Summary Points
- Knowing that spousal bereavement is linked to increased morbidity and mortality, Chirinos et al designed a study involving 54 widows/widowers and 47 matched controls to determine if sleep disturbance during bereavement is associated with increased markers of inflammation.
- In initial analysis and after adjusting for depression, sleep disturbance was not significantly associated with increased levels of C-reactive protein, a marker for inflammation.
SYNOPSIS: This study investigating the association of sleep disturbance with increased markers of inflammation in widows and widowers compared to controls found that self-reported sleep disturbances are more strongly correlated with increased markers of inflammation in bereaved individuals.
SOURCE: Chirinos DA, Ong JC, Garcini LM, et al. Bereavement, self-reported sleep disturbances, and inflammation: Results from Project HEART. Psychosom Med 2019;81:67-73.
Death remains an inevitable fact of life. However, the medical field has made significant progress in understanding the many ways that death affects those close to the deceased. One area of particular concern is spousal bereavement, which has been linked to a higher risk of inflammatory conditions and increased morbidity and mortality among those who recently have lost a spouse.1
Wondering if part of the reason for increased inflammatory disease in this population is related to sleep disturbance after the death of a spouse, Chirinos et al designed a cross-sectional study to investigate the relationship between self-reported sleep disturbances and inflammation to determine whether bereavement status affects this association.
Studies have shown that sleep disturbances often are associated with increased inflammation markers, including C-reactive protein (CRP) and interleukin-6 (IL-6).2 However, only a few studies have explored this link in older adults who experience both sleep issues and chronic inflammatory conditions, such as cardiovascular disease (CVD). Stress can lead to an exaggerated inflammatory response, and the death of a spouse is a highly stressful event.1-3 Therefore, Chirinos et al hypothesized that individuals who have lost a spouse may have a significantly higher inflammatory response to sleep disturbance than age-matched controls.
A total of 54 bereaved and 47 control individuals were recruited for this Houston-based study via online postings, fliers, support groups, and community gatherings. Exclusion criteria included having any inflammatory disease and loss of a spouse (via death or divorce) within five years for participation in the support group. The mean time of bereavement in the widow/widower group was 89.6 days (standard deviation [SD] = 15.9 days).
The Pittsburgh Sleep Quality Index (PSQI), a well-established questionnaire that evaluates the degree of self-reported sleep disturbances, was used to measure sleep. This instrument allows calculation of a global score, as well as three subcategories: sleep efficacy, perceived sleep quality, and daily disturbance or daytime dysfunction.4 For each of the subcategories and the global score, higher scores indicate more dysfunction. High-sensitivity CRP was measured to determine the level of inflammation.5
Given the association of depression with sleep disturbances and with inflammation, depression was measured in all participants using the Center for Epidemiologic Studies Depression Scale.6 Other covariates included comorbid conditions, body mass index, caffeine consumption, and demographic information.
Results
The group demographics of the 101 participants were a group of 54 bereaved patients and a control group of 47 patients. The bereaved and control groups were well matched in age (mean age of group 67.12 years; SD, 12.11), gender (70.30% female); race/ethnicity, years of education, comorbid conditions, caffeine use, antidepressant use, and statin use.
However, the participants in the bereaved group had significantly higher scores in depression scale, PSQI global scale, PSQI Sleep Efficiency, and PSQI Perceived Sleep Quality. CRP, used to measure inflammation, did not differ significantly among the group. Table 1 displays this result.
Table 1. C-Reactive Protein Values by Study Arm |
|
Whole group |
1.40 mg/L (SD, 0.70-3.60) |
Bereaved group |
1.60 mg/L (SD, 0.80-4.40) |
Control group |
1.30 mg/L (SD, 0.60-2.90) |
SD: standard deviation The P value for this comparison was 0.340. |
|
Chirinos et al used regression analysis to statistically investigate the connection between self-reported sleep disturbances and inflammation while considering the effect of multiple variables, including bereavement. The analysis ultimately found the moderating variable to be bereavement status. With further analysis, it became clear that the association between PSQI global score and PSQI sleep efficiency domain were only significantly associated with inflammation in the bereaved group compared with the controls. (See Table 2.)
Table 2. Bereaved vs. Controls (Stratified Regression Analysis) |
||
| PSQI Global Score × B | PSQI Sleep Efficiency × B | |
Bereaved group |
0.104 (0.013-0.196); P = 0.026* |
0.202 (0.053-0.351); P = 0.009* |
Control group |
-0.016 (-0.096 to 0.065); P = 0.690 |
-0.027 (-0.227 to 0.173); P = 0.787 |
B: the “regression coefficient” representing the change in dependent variable (inflammation) with each unit change in PSQI score; PSQI: Pittsburgh Sleep Quality Index *Statistically significant values |
||
Commentary
Bereavement is not a medical condition, per se. However, bereavement is associated with morbidity and mortality and linked to a higher risk of inflammatory conditions, such as CVD; understanding the factors driving this connection has the potential for improving quality of life and extending the lifespans of affected individuals.1-3
Chirinos et al add to our medical knowledgebase about spousal bereavement with this controlled study looking at the association of self-reported sleep disturbance and inflammation and finding that bereavement moderates this association.
As noted by the authors, the limitations of this work include the small sample size, cross-sectional design, and reliance on self-reporting for sleep disturbances. These are among the factors that make the results from this study difficult to generalize and do not allow a conclusion of causality.
However, the results may be considered both preliminary and promising and point to the need for larger studies with a diverse population using objective measures of sleep (such as electronic sleep monitors or even personal tracking devices).
An additional factor to note is that both the global PSQI and sleep efficiency PSQI scores were most strongly associated with inflammation in bereavement, but the two other subgroups (domains) of the PSQI — perceived sleep quality and daytime dysfunction — did not show such an association. The study did not attempt to explain this finding, but it is notable that sleep efficiency measures on the PSQI rely on more objective information (measured in minutes/hours) than the other two domains.
When thinking about potential clinical applications of these findings, it becomes clear that extending the study over time could help uncover if the association between sleep disturbance and inflammation in the bereaved is transitory or more permanent. Such information would help in designing appropriate interventions for the bereaved population.
It also is important to note that this study gives no clinical information on the effect of improving sleep in the bereaved. Future studies will most likely look at the trend of CRP or other measures of inflammation if sleep is restored or improved in the risk group (widow or widower) or conversely may investigate if sleep improves with interventions designed to decrease inflammation.
Notably, many surviving spouses often report alterations in their daily routines after the death of a partner. These modifications may encompass not only disruptions in sleeping patterns, but also changes in eating behaviors, physical activity, and socialization. Moreover, often these changes lead to a less healthy way of life and also may influence the overall inflammatory state.7 As a result, it may be useful to incorporate such variables into future studies, since improving sleep alone may not address other potentially damaging life changes.
At present, the study’s practical uses may be limited, but integrative providers still can use it to address the needs of those who recently have experienced a loss. By asking questions about sleep efficiency (for example, how long it takes a patient to fall asleep and how frequently and for how long a patient wakes up during the night), providers can provide interventions and patients can track their own sleep habits.
Informing patients that early evidence suggests that sleep problems in the bereaved can lead to inflammation and may affect health can motivate improvement in sleep hygiene. Overall, adding a focus on sleep to bereavement support plans may be one of the best ways to use the study’s findings.
References
- Ennis J, Majid U. “Death from a broken heart:” A systematic review of the relationship between spousal bereavement and physical and physiological health outcomes. Death Stud 2021;45:538-551.
- Irwin MR. Sleep and inflammation: Partners in sickness and in health. Nat Rev Immunol 2019;19:702-715.
- Brown RL, LeRoy AS, Chen MA, et al. Grief symptoms promote inflammation during acute stress among bereaved spouses. Psychol Sci 2022;33:859-873.
- Buysse DJ, Reynolds CF 3rd, Monk TH, et al. The Pittsburgh Sleep Quality Index: A new instrument for psychiatric practice and research. Psychiatry Res 1989;28:193-213.
- Sproston NR, Ashworth JJ. Role of C-reactive protein at sites of inflammation and infection. Front Immunol 2018;9:754.
- American Psychological Association. Center for Epidemiological Studies: Depression. Published 2011. https://www.apa.org/pi/about/publications/caregivers/practice-settings/assessment/tools/depression-scale
- Infurna FJ, Wiest, M, Gerstorf D, et al. Changes in life satisfaction when losing one’s spouse: Individual differences in anticipation, reaction, adaptation, and longevity in the German Socio-economic Panel Study (SOEP). Ageing Soc 2017;37:899-934.
This study of the association of sleep disturbance with more markers of inflammation in widows and widowers compared to controls revealed self-reported sleep disturbances are more strongly correlated with increased markers of inflammation in bereaved individuals.
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