Sad and lonely at bedtime - stress hormone up at dawn

According to a new study older people who go to bed lonely, sad or overwhelmed wake up the following morning with elevated levels of cortisol, the stress hormone linked to depression, obesity and other health problems.

The study which examines 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 depressed and feeling unable to cope they have elevated levels of cortisol shortly after waking the next morning.

This is thought to prepare the body on a day-to-day basis to deal with negative experiences.

Cortisol helps the body to raise blood sugar levels and blood pressure in response to stress but also causes changes in mood and memory.

Emma K. Adam, the lead investigator of the study says the morning cortisol boost could help adults who went to bed with troubled or overwhelming feelings face the world the next day and have positive social experiences that help regulate hormone levels.

Adam, an assistant professor of education and social policy and faculty fellow at the Institute for Policy Research at Northwestern University, Illinois, says cortisol is often considered as a negative hormone because of evidence, mostly in animal models, that long-term elevations could be potentially harmful to physical health.

But in the short term the stress hormone is adaptive and helpful as it helps us respond to stressful experiences and do something about them and is necessary for survival.

Cortisol levels are generally high immediately upon waking, increase in the first 30 minutes after waking and then decline to low values at bedtime.

Adam, with her colleagues John T. Cacioppo and Louise C. Hawkley at the University of Chicago, and Brigitte M. Kudielka from the University of Trier, Germany, showed that changes in this pattern from one day to the next are closely interwoven with changes in our daily experiences.

The study, based on data from the Chicago Health, Aging, and Social Relations Study (CHASRS) at the University of Chicago includes 156 older adults living in Cook County who were born between 1935 and 1952 from a range of socioeconomic classes.

Their cortisol levels were measured from small samples of saliva provided three times a day for three consecutive days and the participants reported their feelings each night in a diary.

The researchers then compared cortisol levels on a particular day in order to see if they were predicted by experiences the day before or were predictive of experiences that same day.

Adam and her team found that people who experience anger throughout the day have higher bedtime levels of cortisol which appeared to indicate a biological signature of a bad day.

The study provides evidence that cortisol also plays a role in influencing our experiences.

Individuals with lower levels of cortisol in the morning experienced greater fatigue during the day, a result with potential implications for understanding chronic fatigue.

The study appears in the Proceedings of the National Academy of Sciences.