Work package 3 – Psychobiological mechanisms of stress, restitution and health perception (laboratory studies)

SP 3.1 Sleep quality, stress and health perception

Sleep is thought to be a central mediator of stress related diseaseses. This SP focuses on the link between stress and sleep and the consequences of inadequate sleep. Senior Researechers: Åkerstedt, Lekander, Alexandersson, Kecklund.

• One study (P) utilizes a longitudinal field study of 400 women recorded with polysomnography (PSG) (home-recording) twice with 10-years between the measurements. Data will be used to study how changes in PSG during aging (and with stress exposure) relate to changes in subjective sleep complaints in women. Also depression, burnout, sleepiness, subjective health, proinflammatory cytokines and sickness absence will be studied. (R+P)
   
• A second study (P) will investigate how experimental sleep fragmentation affects sleepiness using functional magnetic resonance imaging (fMRI), sleep latency tests, cytokines and endocrine parameters. (R+P)
   
• A third subproject (O) investigates acute effects of one night of sleep loss on the same parameters as the previous ones. (P+R)
   
• A fourth study (P) will focus on experimental sleep fragmentation in a field setting based on a day-to-day monitoring of sleep using one-electrode PSG (conditional on validation testing of the PSG device). (R+P)
   
• A fifth study (O+) investigates the effects of chronic partial sleep loss (4h/day for 5 days) on social interaction and immune, endocrine, health and other parameters. (P+R)

SP 3.2 Influence of stress exposure on the autonomous nervous system, immune regulation and transmittor substances

The project is based on the fact that few high quality system-based investigations of how exposures to stress or distress affect homeostasis and regulation in the nervous and the immune systems have been performed. Senior Researchers: Axelssson, Hillert, Lekander, Svartengren, Åkerstedt, Perski.

• In one study (O) in twins, the impact of hearing related stress and stress sensitivity and genetic factors on sympatho-vagal balance and sleep quality is investigated longitudinally. (O+R+E)
   
• A second study (P) will use newly developed methods to measure efficiency of glucocorticoid inhibition (stress hormone sensitivity) on cytokines and regulation of the immune system with eight color flow cytometry (FACS). (P+R)
   
• In a third study (P) pain thresholds and sleep quality as predictors of future sickness absence will be studied in subjects with musculoskeletal pain. (O+R)

SP 3.3 Inflammation, sickness behavior and subjective health

Stress, infection and disrupted sleep cause inflammatory responses that are interpreted by the brain as sickness signals and activates a hormonal stress response. Such signaling causes behavioural responses of importance for subjective ill-health, but are little investigated in humans. Senior Researchers: Axelsson, Lekander, Åkerstedt, Kecklund.

• In one study (P) the impact of chronic (allergy) inflammation on brain function (fMRI or PET) will be investigated, as well as subjective health, stress, tiredness, pain regulation, appearance and gait. (P+R+E)
   
• In another study (O) experimentally induced inflammation will be used to study its effects on the same parameters. (P+R)

SP 3.4 Burnout/exhaustion syndrom

The burnout/exhaustion syndrom is considered an end result of longterm exposure to stress. The biological mechanisms are unknown. In this SP we investigate the number of receptors in patients compared with controls. Senior Researcher: Perski.

• In one study we focus on serotonin receptors. In a second we focus omn GABA, and in a third on histamine. (R+E+Stockholm Brain Institute)