Insufficient sleep and marital conflict heighten inflammatory responses, new research shows.
Investigators led by Stephanie Wilson, PhD, Ohio State University Institute for Behavioral Medical Research, Wexner Medical Center, Columbus, found that although baseline inflammatory levels did not differ between those who received sufficient sleep and those who did not, the inflammatory response increased after a difficult marital discussion in those who had insufficient sleep.
When both partners had slept less, their behavior during conflict was more negative. However, sufficient sleep — even in one partner — conferred protection against these adverse behaviors. Moreover, couples who demonstrated emotional regulation did not demonstrate an elevated inflammatory response.
"Sleep is important in many ways, and its effects can be transmitted across partners. Couples were hostile toward each other only if both partners had less sleep than the recommended 7 hours per night. Otherwise, the well-rested partner helped to neutralize the argument. Conversely, a partner who used healthy emotion regulation strategies could neutralize the effect of diminished sleep on inflammation in both partners," Dr Wilson told Medscape Medical News.
The study was published in the May issue of Psychoneuroendocrinology.
Sleep, Inflammation, Conflict
Diminished sleep contributes to premature mortality and is also implicated in cardiovascular disease, cancer, obesity, and diabetes, the authors write. They note that an expert consensus panel recommended 7 to 9 hours of sleep nightly to preserve health in adulthood. Moreover, short sleep duration may "independently exacerbate inflammatory responses to stressors."
Although previous research has shown that sleep problems can provoke hostility in couples, findings have been inconsistent as to whether sleep problems may also disrupt emotional regulation strategies, such as expression (conveying feelings with words and nonverbal gestures) and cognitive reappraisal (thinking about an upsetting situation from a different perspective).
"Because regulation strategies directly affect interpersonal communication, conflict, and intimacy between partners, the question of whether they are reduced by or buffer the effects of short sleep is important; the two hypotheses have not been tested together in a single sample," the investigators write.
Additionally, "sleep is dyadic for many adults," the authors point out. They note that there is a "surprising dearth of studies" regarding short sleep duration and inflammation in couples and that having a bed partner affects the quality and quantity of one's sleep.
Previous research demonstrated that one partner's shortened period of sleep can affect the health and well-being of the other partner — a trend that might be attributed to inflammatory changes.
"We know from prior research that sleep problems can boost inflammation under extreme conditions and also that a couple's relationship can influence their health. But this link has not been explored," Dr Wilson said.
To investigate the relationship between short sleep duration, inflammation, and marital discord, the researchers investigated the effects of husbands' and wives' self-reported sleep duration on both partners' inflammation level and reactivity to marital conflict. They tested the effect of both partners' short duration of sleep on their behavior and emotional regulation during conflict, and they examined emotional regulation strategies as outcomes of sleep and as buffers of the sleep-inflammation relationship.
The researchers recruited couples from a parent study of immune responses to high-fat meals that was conducted by Janice Kiecolt-Glaser, PhD, director of the Institute for Behavioral Medicine and Research. The final sample included 43 couples (n = 86 participants). The mean age of the participants was 38.2 years (SD, 8.2; range, 24-61). All of the couples were married, with a mean length of marriage of 11.5 years (SD, 6.6; range, 3-27).
Participants completed two full-day study visits at the hospital research unit. At the beginning of one visit, they ate a meal high in saturated fats, and at the beginning of the other, they ate a meal high in oleic sunflower oil.
They were instructed to avoid alcohol and caffeine within 1 day prior to their visit and to avoid physical activity within 2 days prior to their visit. They were also instructed to discontinue use of aspirin and dietary supplements for 7 days prior to each visit.
On the day before their visit, they received three standardized meals designed to reduce any variability in inflammation that might be associated with recent food intake. They were also required to fast for 12 hours prior to their visit.
Blood samples were collected upon arrival and approximately 1 hour after the conflictual discussion.
The researchers collected data on the past two nights' self-reported sleep duration, self-reported emotional regulation during conflict, chronic sleep problems (measured by the Pittsburgh Sleep Quality Index), marital quality (measured by the Couple Satisfaction Index), and depressive symptoms (based on the Center for Epidemiological Studies Depression Scale).
Discussions of marital disagreement were coded using the Rapid Marital Interaction Coding System.
Inflammatory cytokines that were measured were interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α).
Among the couples, sleep duration from the previous night ranged from 3.5 to 9 hours, but for almost half of the couples, the duration fell below the 7-hour threshold.
The researchers found that short sleep duration did not relate to baseline morning inflammation for each individual or his/her partner. Interactions between both partners' sleep were also not significant, and effects did not differ by participants' sex.
In the fully adjusted statistical model, effects of sleep on one's own IL-6 level (B = -0.057; SE = 0.024; P = .02) and TNF-α production (B = -0.057; SE = 0.026; P = .03) were significant. Individuals who slept 1 hour less than average had 6.0% higher IL-6 and TNF-α production following the conflictual interaction.
Interactions between the recent sleep of both partners were not significant for either IL-6 or TNF-α levels. The effects did not differ by sex. Including the conflict behavior of either partner as a covariate did not change the statistical significance of recent sleep on one's own post-conflict inflammation level.
Interactions between partners' sleep were statistically significant predictors of positive and negative behavior (P = .01 for both).
In reduced models, sleep did not relate to one's own emotional expression or reappraisal strategies during conflict. However, shorter sleep duration significantly predicted diminished reappraisal use during conflict (B = 0.44; SE = 0.207; P = .04).
The effect of recent sleep on IL-6 level following conflict was significantly moderated by the individual's own expression of emotion (B = 0.025; SE = 0.011; P = .03). Moreover, those who expressed less emotion during the conflict and who had also slept less had higher post-conflict IL-6 production compared to people who slept more (Slope = -0.10; SE = 0.031; P = .001). Even 1 hour less of sleep had an impact: participants with low emotional expression who slept 1 hour less than average had 11% higher IL-6 production following conflict.
On the other hand, for persons with high emotional expression, the connection between shorter sleep and higher IL-6 production was less (P = .52). Individuals with less expressive partners who also slept 1 hour less than average had 11% higher IL-6 production. Similarly, individuals whose partners engaged in a lower degree of reappraisal and who slept 1 hour less than average had 9% higher IL-6 production.
"These findings suggest that the risks of short sleep in daily life lie in heightened inflammatory sensitivity to stressors rather than elevated next-morning inflammation, and that these risks depend on both partners' sleep and emotion regulation strategies," the authors write.
These results were surprising, said Dr Wilson.
"We initially expected that people who slept less in the last 2 nights would come into the study with higher baseline inflammation, but that is not what we saw. Instead, the elevations in inflammation were in response to marital disagreement."
She called it a "two-hit situation," in which "the first source of vulnerability is loss of sleep. And then, if one encounters a stressor like marital disagreement, that creates the higher risk category of having the inflammatory response."
Ask About Couples' Sleep
Commenting on the study for Medscape Medical News, Kathi Heffner, PhD, associate professor of nursing and psychiatry, University of Rochester Medical Center, New York, called the study "novel."
"These findings suggest that less sleep may play a role in reducing the quality of marital relationships. In addition, it underscores the emotion regulation strategies that can buffer any impact of sleep on the way people respond to marital stressors," said Dr Heffner, who was not involved in the study.
She expressed surprise that the authors did not find associations between sleep duration and morning inflammatory response, as has been found in prior research, "suggesting that we should pay more attention to the role of sleep in the way our bodies respond to interpersonal stressors, specifically."
There are important clinical implications to the study findings, she emphasized. "Clinicians working with couples may want to evaluate spouses' sleep habits, as they may be playing a role in marital quality."
Moreover, "inadequate sleep may be an additional target of intervention to promote marital quality and health.
"It is common for people to get less than 7 hours of sleep and not uncommon to get into marital spats that come up in the daily lives of ordinary couples and have measurable effects. Clinicians should think about the sleep hygiene of the couple when looking at the health of the marital relationship."
The study was supported in part by the National Institutes of Health, a Pelotonia Postdoctoral Fellowship from the Ohio State University Comprehensive Cancer Center, and a postdoctoral fellowship grant from the American Cancer Society. The authors have disclosed no relevant financial relationships.
Psychoneuroendocrinology. 2017;79:74-83. Abstract
Medscape Medical News © 2017
Cite this: Lack of Sleep Plus Marital Strife Ups Inflammation - Medscape - Jun 30, 2017.