Characterizing sleep-related complaints in head and neck cancer survivors with tumors of airway relevance following radiotherapy.

Stress arises if an individual's physiological or psychological integrity is perceived as threatened, eliciting physiological and/or behavioral reaction []. Physical stressors (e.g., prolonged exercise, electric shock) and psychological stressors (e.g., public speaking) [], their interpretation, as well as stress responses vary across individuals [], especially in the case of psychological stress due to a lack of control or predictability []. For maintenance of homeostasis, the activation of stress response induces endocrine alterations. The central effectors of the stress response are a rapid activation of the sympatho-adrenomedullary system (SAM), followed by a delayed activation of the hypothalamic-pituitary-adrenal-axis (HPA axis). During acute stress, Corticotropin-releasing hormone (CRH) is synthesized in the hypothalamus and released into the hypophysial portal system, inducing the release of adrenocorticotropic hormone (ACTH) in the adenohypophysis. Once ACTH is released into the bloodstream, it stimulates cortisol synthesis and secretion in the adrenal cortex, which can further inhibit the activity of the HPA axis via a negative feedback loop [,]. While stress per se is not always harmful, an adaptive response to stress can be beneficial, such as preparing for fight or flight reaction. Especially chronic stress is associated with various psychological and physiological illnesses such as depression [], cardiovascular disease [], or metabolic diseases []. However, the underlying molecular mechanisms are still largely unknown. This is particularly concerning given that stress has been highly prevalent during the recent COVID-19 pandemic [] and that psychosocial stress, to which individuals are increasingly exposed in today's society, tends to last longer and cannot be relieved as quickly as stress due to acute physical threats [].