Happiness

We used data that had been collected previously for a study of the validity of the Japanese version of the SF-36, and calculated national norm scores of all subscales of the SF-36 [8 (link),9 (link)]. Details of the nationwide survey have been described previously [9 (link)]. Briefly, a total of 4500 people 16 years old or older were selected from the entire population of Japan by stratified-random sampling in 1995. A self-administered questionnaire was mailed, and the subjects were visited to collect the questionnaires. The SF-36, the ZSDS [11 (link)] (described below), and questions about demographic characteristics were included in the questionnaire.
The ZSDS consists of 10 positively worded items and 10 negatively worded items asking about symptoms of depression. Several studies have established the ZSDS as a reliable and valid instrument for measuring depressive symptoms [12 (link)-14 (link)]. The ZSDS scores were used to define four categories of the severity of depression: within normal range or no significant psychopathology (below 40 points); presence of minimal to mild depression (40–47 points); moderate to marked depression (48–55 points); presence of severe to extreme depression (56 points and above). These score ranges result from the studies of Zung [15 (link)] and Barrett et al [16 (link)]. The ZSDS has been translated into Japanese and studies of the validity of the Japanese version have been published [17 (link)]. Because the ZSDS is not a clinical diagnostic tool, subjects with high scores are said to have depressive symptoms rather than "depression."
Like the rest of the SF-36, the MHI-5 was administered as a paper-and-pencil questionnaire. The instrument contains the following questions: 'How much of the time during the last month have you: (i) been a very nervous person?; (ii) felt downhearted and blue?; (iii) felt calm and peaceful?; (iv) felt so down in the dumps that nothing could cheer you up?; and (v) been a happy person?' For each question the subjects were asked to choose one of the following responses: all of the time (1 point), most of the time (2 points), a good bit of the time (3 points), some of the time (4 points), a little of the time (5 points), or none of the time (6 points). Because items (iii) and (v) ask about positive feelings, their scoring was reversed. The score for the MHI-5 was computed by summing the scores of each question item and then transforming the raw scores to a 0–100-point scale [18 ].
Items (i) and (iii) are almost identical to 2 items in the Zung Self-rating Anxiety Scale [10 (link)]. To make a scale that is even shorter than the MHI-5 and is focused on depression we removed those two anxiety-related items. Thus, the MHI-3 comprised only (ii), (iv), and (v) above. Possible scores on the MHI-3 ranged from 3 to 18 points.

Women leaving home or becoming homeless at an early age were particularly vulnerable to predatory relationships with older men or romantic relationships of necessity and convenience. Prior studies found a particular association between intimate relationships as a source of increased violence and transitions into injection drug among females [67 (link)]. Consistent with these findings the women in this study frequently described how partners introduced them to drugs and were the catalyst to transition into “harder” drugs:

met a guy who was like 29 and he gave me heroin, like I’d never touched drugs in my life, he injected me, with heroin. I know. I had crack. I didn’t really know what I was taking. He introduced me to heroin at 15 (Gillian).

Intimate relationships were often based on the need for protection: “[partner’s name] is there all the time cos she protects us. She makes us like get up in the mornings and try and get ready and get washed, and stuff like that and she’ll like cooks for us and like she is there. If she hadn’t have been, I wouldn’t be here” (Carina).
Several women met their partners through drug networks and were subsequently coerced into drug dealing: [I met him] through different people in […], who were selling drugs and people knowing people and me being young he swept us off my feet, wined and dined us and I was a lot younger and – he used us basically, to his advantage. “Well if you do this, do that, I’ve got me third strike I’m out, you’ll have to sell this and that” (Delia).
Gillian illustrates the difficulty of getting away from the pull of street culture. Having had a relatively happy and stable relationship for several years, coinciding with better mental health, a job and sense of purpose, the end of that relationship swiftly led to her going back to where she felt a “connection”, a drug dealer who knew her which she associated with having a sense of belonging:

When I was with [partner] and we were both PT [Personal Trainers] everything was fine … my life was absolutely the best … No domestic violence or nothing. I was just happy … I was drug free, like totally, just normal just normal shit and he broke my heart and that and I ended up, like not back on heroin just crack. I started using cocaine and drinking and that you know, cos he left us. And then from then I went out like a coke dealer who I knew from all them years ago when I had [...] who used to serve us up. And I felt like a connection with him cos he knew us (Gillian).

Intimate relationships were entered into out of necessity, following crisis points (homelessness, death of previous partner) and women described partners exacerbating drug use, or precipitating further trauma and abuse.

The Japanese version of the UMACL was used to evaluate the mood of comfort [23 ]. The original checklist, developed by Matthews et al., was created based on dimension theory, making it possible to assess arousal levels [24 (link)]. The scale has two subscales that can be used to evaluate energetic arousal (10 items; vigorous vs. tired: coefficient α = 0.79) and tense arousal (10 items; nervous vs. relaxed: coefficient α = 0.76) [25 ]. High energetic arousal represents active and happy, whereas low tense arousal represents calm and quiet. Participants were asked to respond on a 4-point Likert scale. In a previous study, the mean energetic arousal was 24.4 (standard deviation [SD]: 0.5) for males and 24.4 (SD: 0.4) for females, and the mean tense arousal was 18.5 (SD: 0.4) for males and 17.56 (SD: 0.3) for females [25 ].

Study design and period
A retrospective cross-sectional study was carried out among individuals who had or are currently following the IF. In the four-week preparation period, we created our study title, reviewed the literature to gather information on typical side effects and how to measure the quality of life, and created a questionnaire. In the following four weeks, we completed our research, which included looking for the target group on social media, creating a Google Form for the survey, and testing the form by using a small sample of the findings to make sure they presented as we planned. We collected and examined our data for a further four weeks before writing our report.
Inclusion and exclusion criteria
The study includes people who have ever practiced or are currently practicing IF and who can speak the Arabic language. The target population is in Saudi Arabia in all regions of the kingdom. The initial assessment questions excluded participants who had never engaged in IF. The sample size was calculated automatically using Google Forms. A total of 300 people were registered in the Google Form; 147 of them had practiced IF, and 153 were excluded.
Data collection tool
We developed a questionnaire in Arabic to collect data about IF attitudes and quality of life (questionnaire in the Appendices section). The questionnaire was developed to meet the health-related quality of life (HRQOL) measures, which were translated into Arabic to be suitable for the participant's understanding of the question in our survey. The Centers for Disease Control and Prevention (CDC) HRQOL-4 measures had acceptable test-retest reliability and strong internal validity, which has been used by the CDC and its partners, for tracking population health status and HRQOL measures in states and communities [8 ]. The standard four-item set of healthy days’ core questions was developed by the CDC. The questionnaire consists of the following four main parts: (i) sociodemographic data, (ii) side effects assessment, (iii) participants' attitude toward IF assessment, and (iv) participants' quality of life assessment.
Data collection technique
We conducted the survey in an electronic self-assessment format using Google Forms. We targeted IF groups on social media in Saudi Arabia for a time interval of four weeks through messages and direct contact with the group administrator and ensured that only people who practiced IF participated in the survey. One of the first questions in the survey was “Have you tried Intermittent fasting?” If the answer was no, then the participant is excluded from the survey. The data obtained from the survey were reviewed and automatically copied into a personal computer.
Data entry and analysis
The data collected using the questionnaire was rearranged in Microsoft Excel data sheets. The data was mainly expressed as numbers and percentages. We used a chi-square test to evaluate participants’ perceived happiness, which also indicated the p-value for statistical significance. We also used a pie chart that displays the change in the participants’ body weight following their adoption of IF and to seek the perceived happiness of the participants' IF experience.
Ethical considerations
This study was approved by the Bioethics Committee for Scientific and Medical Research at the University of Jeddah (Approval number UJ-REC-069). Individual consent was required prior to data collection, and it was stated on the questionnaire's front page that completing it signified consent to participate in the study. All information was kept private and was solely utilized for scientific studies. Furthermore, we made sure that parental consent was given to participants less than 18 years old.