Relationship of Sleep Quantity and Quality with 24-Hour Urinary Catecholamines and Salivary Awakening Cortisol in Healthy Middle-aged Adults

Zhang J; Ma RCW; Kong APS; So WY; Li AM; Lam SP; Li SX; Yu MWM; Ho CS; Chan MHM; Zhang B; Wing YK. Relationship of sleep quantity and quality with 24-hour urinary catecholamines and salivary awakening cortisol in healthy middle-aged adults. SLEEP 2011; 34(2):225-233.

Short sleep duration is a huge problem affecting modern society. It is associated with cardiovascular problems, metabolic disturbances, hypertension, diabetes, and many other grave illnesses.  Despite all of these and many other associations, the pathophysiologic mechanism in mediating poor sleep and various medical problems remains unclear.

Sleep deprivation is considered to be a form of stress. The hypothalamic-pituitary-adrenal axis (HPA) and locus ceruleus-norepinephrine-autonomic system are two of the brain systems involved in stress-response. Normal sleep decreases the sympathetic nervous system activity (arousing) and increases the parasympathetic nerving system activity (calming).

In this study, researchers aimed to: 1. “explore the level of stability in sleep/wake patterns of middle-aged adults over a three-year follow up period” and 2. “explore the relationship of sleep quantity and quality as measured by actigraphy with 24 hour urinary catecholamines and 3-day salivary awakening cortisol”.

This study was part of a large epidemiologic study that started back in 2003, regarding children and their parents sleep quality. After participants that could not participate in this particular study were ruled out, the sample contained 96 valid subjects with at least one day of actigraphy, 98 subjects with a valid 24-hour urinary catecholamine, and 101 subjects with valid 3-day salivary cortisol results. There was some overlap between these three groups.

The participants filled out detailed questionnaires, a consecutive 2-week sleep log, physical examinations, a 3-day actigraphic assessment, a 3-day morning salivary awakening cortisol, and a 24-hour urinary catecholamine collection. During the physical examination, weight, height, waist circumference, hip circumference, BMI, blood pressure, and a blood sample were measured. Sleep/wake patterns were measured through the consecutive two-week journals. Researchers asked the participants to record the time they went to bed and got up every day for the two-week period. From these records, each participant’s wake up time, bed time, and duration of time in bed was averaged. Researchers utilized an actigraphy wristwatch to measure participants’ time in bed, actual sleep duration, sleep onset latency, wake after sleep onset, and sleep efficiency. Researchers instructed all participants to collect 24 hour urinary samples during the time that they were completing actigraphic assessment so that the researchers could look for an association between objective sleep parameters and cacatecholamine levels. Researchers also had participants collect three saliva samples on three separate days right after they awoke.

Results of statistical analysis showed that there was a high correlation between baseline and follow up measures of various sleep/wake patterns, (r = 0.79 for bedtime, r = 0.64 for wakeup time, and r = 0.60 for time in bed, respectively, p < .001). There were moderate to high correlations in sleep/wake patterns between the participants’ two-week sleep logs and 3-day actigraphy measures, r = 0.43, 0.48, and 0.81 for wake-up time, time spent in bed, and bedtime, respectively, p < .001). Poor sleepers had higher levels of stress hormones in their urine. A lower three-day awakening cortisol level was found in participants that had a lower amount of time in bed than in subjects that had a higher amount of time in bed. Among male and female poor sleepers, males had a higher amount of stress hormones in their urine samples. Among the actigraphic results, sleep onset latency was significantly correlated with higher BMI, waist/hip ratio, systolic blood pressure, and diastolic blood pressure. The urinary hormone levels were positively correlated with waist/hip ratio and diastolic blood pressure.

            The researchers proposed that the level of stability of sleep patterns across the two year time-span could mean that unhealthy sleep patterns could have a persistent effect on a person. The increased hormones in the 24 hour urine samples suggest that the sympathetic nervous system may indeed by stimulated by poor sleep quality and duration.