A new study that takes a rare look at the physiological, social and emotional dynamics of day-to-day experiences in real-life settings shows that when older adults go to bed lonely, sad or overwhelmed, they have elevated levels of cortisol shortly after waking the next morning.
Elevated levels of cortisol – a stress hormone linked to depression, obesity and other health problems when chronic — actually cue the body on a day-to-day basis that it is time to rev up to deal with loneliness and other negative experiences, according to Northwestern University’s Emma K. Adam, the lead investigator of the study.
In 156 older adults, day-to-day variations in cortisol diurnal rhythms were predicted from both prior-day and same-day experiences, to examine the temporal ordering of experience-cortisol associations in naturalistic environments.
Diary reports of daily psychosocial, emotional, and physical states were completed at bedtime on each of three consecutive days.
Salivary cortisol levels were measured at wakeup, 30 min after awakening, and at bedtime each day.
Multilevel growth curve modeling was used to estimate diurnal cortisol profiles for each person each day. The parameters defining those profiles (wakeup level, diurnal slope, and cortisol awakening response) were predicted simultaneously from day-before and same-day experiences.
Prior-day feelings of loneliness, sadness, threat, and lack of control were associated with a higher cortisol awakening response the next day, but morning awakening responses did not predict experiences of these states later the same day.
Same-day, but not prior-day, feelings of tension and anger were associated with flatter diurnal cortisol rhythms, primarily because of their association with higher same-day evening cortisol levels. Although wakeup cortisol levels were not predicted by prior-day levels of fatigue and physical symptoms, low wakeup cortisol predicted higher levels of fatigue and physical symptoms later that day.
Results are consistent with a dynamic and transactional function of cortisol as both a transducer of psychosocial and emotional experience into physiological activation and an influence on feelings of energy and physical well-being.
In all of her work, Adam is interested in how people’s changing social environments get under the skin to influence their biology and health. “Stress systems are designed to translate social experience into biological action,” she said. “They are designed to be a conduit from the outside world to our internal worlds so that we can better respond to our social context. The overarching question of my studies of these systems in a variety of contexts is whether overuse of these systems plays a role in disease outcomes.”