Table 1.

Overview of the questionnaires being used

Instrument	Content	Length
PSS-10: Perceived Stress Scale (primary outcome measure)	Primary objective Developed by Cohen, Kamarck, and Mermelstein, translated and validated by Klein, Brähler et al., 2016 [47]. Investigates the degree to which life was unpredictable, uncontrollable, and overwhelming within the last month. Very good internal consistency (a = .84). Positive correlation with depression and anxiety, negative one with quality of life.	10 items
DERS-SF: Difficulties in Emotion Regulation Scale Short Form	Measures emotion (dys-)regulation multidimensional. According to the model by Gratz and Roemer [48], the subscales “non-acceptance”, “problems with target oriented behaviour”, “impulsive conduct problems”, “lack of emotional awareness”, “limited access to emotion regulation strategies”, and “lack of emotional clarity”.	16 items
SCS: Self-Compassion Scale	The Self-Compassion Scale was developed by Neff in 2003 with 26 items. The shortened version showed satisfactory to good psychometric properties so far [49].	12 items
WHO-5: WHO Fragebogen zum Wohlbefinden	The facets of psychological well-being like mood, interest, energy, and drive within the last 2 weeks are assessed. Used worldwide, non-invasive questions, translated in 30 languages, the first version was published in 1998. Very good internal consistency with α = .85. German version by Allgaier [50].	5 items
PHQ-4: Gesundheitsfragebogen für Patienten – Depressionsmodul	The PHQ-4 is a valid screening instrument for symptoms of depression and anxiety symptoms (Cronbach α >0.80) [51]. Responses are scored as 0 (“not at all”), 1 (“several days”), 2 (“more than half the days”), or 3 (“nearly every day”). PHQ–4 scores go from normal (0 –2) to mild (3–5) to moderate (6–8) to severe (9 –12). Symptoms within the last 2 weeks are being interrogated.	4 items
DSHI-9: Deliberate Self-Harm Inventory	An initial question is asked whether someone has already intentionally injured his-/herself. If this is answered with yes, the type, onset, and frequency of self-harm are obtained [52].	1–6 items
ISI: Insomnia Severity Index	Measures the quality of sleep and goes back to [53]. Difficulties falling asleep or staying asleep and the impairment they cause in everyday life are in the focus.	7 items
SEED: Short Evaluation of Eating Disorders	It obtains the central symptoms of anorexia (underweight, fear of weight gain, impaired body awareness) and bulimia (binge eating, compensatory measures, excessive preoccupation with figure and weight) within the last month [54]. It has already been used in student samples with good experience.	6 items
SFF: Schutzfaktoren	This short questionnaire captures three scales of protective factors that correlate significantly with data from the SDQ. Children who have more social, personal, and family resources are correspondingly less conspicuous in the SDQ [55].	12 items
SISE: Single-Item Self-Esteem Scale	This 1-item version goes back to the 10-item scale of the Rosenberg Self-Esteem Scale (RSES) developed by Rosenberg in 1965. The original sheet captured self-esteem with 5 positive and 5 negative questions. Recent studies have also demonstrated very good measurement properties for the 1-item version [56]. The question asks how well the statement “I have high self-esteem” applies to oneself. A 4-point Likert scale is then presented.	1 item
CD-RISC-10: Connor-Davidson Resilience Scale-short form	The long version was designed by Connor-Davidson in 2003 to measure resilience. Resilience means the ability to cope with internal or external stressors. The CD-RISC is widely used and has good psychometric properties (a = .84) [57]	10 items
FAS III: Family Affluence Scale	The FAS III measures the socioeconomic status using 6 questions and has very good quality criteria. Furthermore, the MacArthur scale question is connected, which asks about the subjective assessment of the prosperity of the adolescents’ own family [58]	6 items + 1