Sleep reactivity to stress and insomnia: sleep measures and molecular markers

Objective. To identify objective measures of sleep and molecular markers of sleep reactivity to stress to determine its role for insomnia prevention and management. Design and methods. The sample included 42 subjects with sleep disturbances and 23 subjects without sleep-related complaints (control group) aged 18 to 72 years. Altogether there are 19 men and 55 women. Nine participants were excluded from the study. Sleep reactivity to stress was assessed using the Ford Insomnia Response to Stress Test (FIRST) questionnaire. The Integrative Anxiety Test was used to screen for anxiety. Sleep indices were assessed by polysomnography (PSG). Blood plasma samples were collected in the morning after PSG to determine brain-derived neurotrophic factor (BDNF), and 24-hour urine was collected one week after PSG to assess metanephrine levels. Results. There were 64 % healthy subjects with low sleep reactivity to stress and low anxiety and 79 % subjects showed insomnia among persons with high sleep reactivity and anxiety. Significant differences in PSG measures were found in groups with low and high sleep reactivity: the efficiency of sleep and the percentage of the second stage of NREM sleep were higher in group with low reactivity, also sleep latency and wake time after sleep onset were lower in group with high reactivity. In addition, serum BDNF level was significantly higher in group with low reactivity, and it correlates positively with daily urinary metanephrine excretion and the absolute duration of stage N3 and negatively with sleep latency. Conclusions. Subjects with high reactivity to stress have lower sleep quality and depth that corresponds to other studies. The level of BDNF is a possible marker of sleep reactivity to stress and it can indicate the potential adaptation to stress.