Stress and Restoration definitions

Stress and restoration are assumed to play a fundamental role in the proposed mechanisms underlying the association between exposures and cognitive development and mental health in children. In general, stress can be defined as “internal or external aversive stimuli that challenge the organism and threaten the homeostasis”, so “stress occurs when homeostasis is threatened or perceived to be so” (Chrousos, 2009). Stressors are the stimuli/situations that can be categorised in physical stressors (e.g. noise or heat), social stressors (e.g. inter-relational conflicts), ecological stressors (e.g. unpleasant housing situation, lack of perceived safety), economic stressors (e.g. financial problems) or occupational stressors (e.g. time pressure, rush) (Bodenmann & Gmelch, 2009). In Equal-Life, most so-called stressors can be conceptualised as aspects of the physical, social and internal exposome.

In general, there are three main approaches to theorise stress: psychological, physiological, and neuro-psycho-biological. Psychological theories emphasise the intervening mechanisms between a stressor and its (long-term) effects. Cohen et al. (2007) describe that “psychological stress occurs when an individual perceives that environmental demands tax or exceed his or her adaptive capacity” (p. 1685). On the other hand, physiological theories emphasise the immediate physiological reaction between stressor and effect. Selye (1974) views stress as “the nonspecific response of the body to any demand” (p. 27). The stimulus stands for the stressor and the response equals stress. Note, that according to this definition stress can be a response to either a positive (challenge, eustress) or negative demand (aversive stressor, distress), indicating the physiological mobilization of the organism to deal with the demand. The physiological perspective of stress, as described here, refers to responses to acute demanding situations. In addition, acute stress indicators, i.e. biomarkers, are relevant and considered as predictors for long term effects (e.g. Babisch, 2002).

This should be distinguished from chronic stress, which is the result of a long-term process of responding frequently to demanding situations that are perceived as harmful or dangerous (primary appraisal); combined with the insight to have less or no control or limited ability or opportunity to cope with these situations (secondary appraisal); also combined with lack of opportunities to recover from such demands (lack of restoration). Chronic stress is closely related to mental (un)well-being and, in the long run, associated with mental illness such as depression (Chrousos, 2009). In consequence, this may mean higher vulnerability or sensitivity to (future) acute demands. Neuro-psycho-biological approaches integrate the first two approaches. Koolhaas et al. (2011) “propose that the term ‘stress’ should be restricted to conditions where an environmental demand exceeds the natural regulatory capacity of an