Table 1

Overview of the main included instruments/variables in the SHoT studies

DomainInstruments and description201020142018
Mental health and well-beingPsychological distress was assessed using The Hopkins Symptoms Checklist (HSCL-25),14 derived from the 90-item Symptom Checklist (SCL-90), which is a screening tool designed to detect symptoms of anxiety and depression. It is composed of a 10-item subscale for anxiety and a 15-item subscale for depression, with each item scored on a Likert scale from 1 (not at all) to 4 (extremely). The period of reference is the past 2 weeks.xxx
Perfectionism was assessed by the short version of the Perfectionism subscale from the Eating Disorder Inventory (EDI).22 x
In SHoT2018 loneliness was assess using an abbreviated version of the widely used UCLA Loneliness Scale, ‘The Three-Item Loneliness Scale (T-ILS)’.23 The Three-Item Loneliness Scale has displayed satisfactory reliability and both concurrent and discriminant validity.x
In ShoT2010 and 2014, social and emotional loneliness were assessed using the Social and Emotional Loneliness Scale,24 which is an extension of the tool originally developed by Russell et al.25 The scale consists of two five-item measures which assess concepts of social and emotional loneliness. Previous psychometric assessments of the coefficient alphas for both constructs of the scale have yielded acceptable values (0.78 and 0.76 for emotional and social loneliness, respectively). When compared with other measures of loneliness (such as the UCLA loneliness scale),26 evaluations of convergent validity for the Wittenberg24 scale yielded acceptable correlation coefficients of 0.81 for social loneliness and 0.59 for emotional loneliness.27 xx
Eating disturbances was assessed by the Eating Disturbance Scale (EDS-5),28 a brief screening instrument for problematic eating in normal populations. The EDS-5 has been shown to have good concurrent and construct validity with respect to DSM-IV eating disorders.x
Quality of life was assessed by the Satisfaction With Life Scale (SWLS).29 The SWLS is a five-item scale designed to measure global cognitive judgments of one’s life satisfaction (not a measure of either positive or negative affect). Participants indicate how much they agree or disagree with each of the five items using a 7-point scale that ranges from 7 (strongly agree) to 1 (strongly disagree).xxx
Positive affect (PA) was assessed by the PA subscale of the Positive and Negative Affect Schedule (PANAS).30 The PA scale includes the terms ‘interested’, ‘alert’, ‘enthusiastic’, ‘excited’, ‘proud’, ‘inspired’, ‘strong’, ‘active’ and ‘attentive’. Participants are instructed to rate the extent to which they usually experience each emotion, rated on a 5-point scale from ‘very slightly or not at all’ to ‘extremely’.x
History of suicidal ideation, suicide attempts and self-harm were assessed with three items drawn from the Adult Psychiatric Morbidity Survey (APMS);31 while questions about self-harm thoughts was adapted from the Child and Adolescent Self-harm in Europe study (CASE).32 If respondents answered yes to any item, timing of the most recent episode, frequency of episodes and age at first onset were then assessed.x
Sleep variables: Typical bedtime, rise time, sleep onset latency (SOL) and wake after sleep onset (WAS) were reported separately for weekends and weekdays. The participants also indicated the number of nights per week they experienced difficulties initiating sleep, difficulties maintaining sleep, early morning awakenings, snoring, breathing cessations during sleep as well as daytime sleepiness and tiredness. Participants were also asked for how long they had suffered from these sleep problems. This information was used as an operationalisation for insomnia disorder, according to the DSM-5 criteria.33 x
Bullying was assessed with the Olweus Bully/Victim Questionnaire34 arguably the most widely used bullying self-report survey in the world.35 Studies using the BVQ have been conducted in at least 15 countries.x
Sexual harassment is commonly defined as unwanted and unwelcome sexual behaviour in a work or educational setting affecting both physical and psychological well-being of a person. It could be evident in three different ways: verbal, physical and non-verbal forms.36 In the current study, sexual harassment was assessed using seven items covering these three forms, also corresponding to the legal definition of Norwegian regulations:

  1. Verbal harassment (sexual expressions and suggestions, comments about body, appearance or private life).

  2. Non-verbal harassment (2a: close eye or body movements, 2b: viewing sexual images (including digital), 2 c: blotting and the like).

  3. Physical harassment (3a: unwanted touching, hugging or kissing, 3b: rape attempt and 3c: rape).

For each of the seven types of harassment, the respondents also indicated who committed the harassment act (fellow student, employed at the educational institution or others), when the harassment was experienced (last month, last year, more than a year ago, but after I started studying and before I started studying) and how many times he/she had experienced to be sexually harassed.		x
Somatic healthSomatic health was assessed by the Somatic Symptom Scale-8 (SSS-8):37 an 8-item reliable and valid self-report measure of somatic symptom burden. Cut-off scores identify individuals with low, medium, high and very high somatic symptom burden.x
Physical and mental conditions were assessed by a predefined list adapted to fit this age cohort. The list is based on a similar operationalisation used in previous large population based studies (the HUNT study) and included several subcategories (not listed here) for most conditions: allergy and intolerances, asthma, cerebral palsy, diabetes, eczema, epilepsy, heart disease, hearing impairments, irritable bowel, cancer, reading and writing difficulties migraine, mental disorders, visual disabilitiesx
Health behavioursAlcohol consumption: Participants assessed with the Alcohol Use Disorder Identification Test (AUDIT).38 The AUDIT consists of 10 items from three domains: consumption patterns (questions one to three), dependence symptoms (questions four to six) and harmful consequences of drinking (questions 7 to 10). Each item has response options that can be scored from 0 to 4. The scores from the 10 items are summarised, yielding a total score ranging from 0 to 40. A total score of 8 (or more) for men and 6 (or more) for women are used to indicate risky drinking and above 13 and 11, respectively, to indicate hazardous drinking.xxx
Physical activity in 2018 was assessed using three sets of questions, assessing the average number of times exercising each week and the average intensity and average hours each time:39

  • ‘How frequently do you exercise?’ (Never, Less than once a week, Once a week, 2–3 times per week, Almost every day).

  • ‘If you do such exercise as frequently as once or more times a week: How hard do you push yourself? (I take it easy without breaking into a sweat or losing my breath, I push myself so hard that I lose my breath and break into a sweat, I push myself to near-exhaustion).

  • ‘How long does each session last?’ (Less than 15 min, 15–29 min, 30 min to 1 hour, More than 1 hour’.

  • Respondents were also asked if they considered themselves to be a ‘top athlete’, and if so, in what sport, and how many hours per week they trained.

Physical activity in 2010 and 2014 was also measures, but not as detailed as in the SHoT2018 study.		(x)(x)x
Illegal drug use was assessed by asking if the participants had used either of the following substances during the last 12 months: amphetamine or methamphetamine, benzodiazepines without prescription (Sobril, Valium and so on) cannabis (hashish/marijuana), ecstasy, GHB, heroin, cocaine, LSD, psilocybin, MDMA, Ritalin without prescription, synthetic cannabinoids (spice) and other drugs. The response options were: Never, 1 time, 2–4 times, 5–50 times. More than 50 times.x
Use of electronic devices at bedtime was assessed using a newly developed questionnaires assessing use a wide range of new electronic devices.40 Adolescents reported use of six different electronic media devices and on whether they used them in the bedroom during the last hour before they went to sleep. Total time spent on screen-based activity during the entire day was also assessedx
Other informationA range of other demographical and background factors were also assessed, including age, gender (male, female, transperson), annual income, economic difficulties, sexual orientation (and problems related to this), relationship status, birth country/ethnicity (self and parents and cultural discrimination based on this), annual, study satisfaction, voluntary work and so on.(x)(x)x