Bódizs R*, Simor P, Csóka Sz, Bérdi M, Kopp MS : Dreaming and health promotion: A theoretical proposal and some epidemiological establishments. European Journal of Mental Health 3: 35-62. 2008 – 2. Methods

2. Methods

2.1. Subjects

Large national representative surveys were conducted in the Hungarian population in 1983, 1988, 1995 and 2002 (KOPP et al. 2000; SKRABSKI et al. 2005). These samples represented the Hungarian population above age 18 according to gender, age, county and 150 sub-regions. Among the 12,640 persons in Hungarostudy 2002, those who agreed to participate in the follow-up study were 4528 persons who were interviewed again in 2005 and 2006 within the framework of the Hungarostudy Epidemiological Panel (HEP) follow-up study. Moreover, additional subjects were enrolled in the 2005/2006 survey in order to balance out some biased aspects of the sample. The total sample of the present study consists of 5009 subjects who answered the Dream Recall Frequency Scale (2682 women, 1832 men; 495 respondents’ sex data are missing), ages varied between 22 and 100 (M = 50.7, SD = 16.4). When answering questions of the survey, subjects usually had the possibility to choose between different options including ‘I do not know’. Those answers referring to the lack of information about dreaming (I do not know) were not included in the analyses of the item in question. Therefore, the number of subjects differed substantially from one analysis to another.

2.2. Measures

Individual differences in dream recall were assessed by the use of the 7-point Dream Recall Frequency Scale (SCHREDL 2004), which is a self-reported measure of usual dream recall rate (Appendix 1).

The Dream Quality Questionnaire consists of items concerning emotional load of dreams, the tendency of experiencing frequent non-recurrent and recurrent nightmares and fearsome nocturnal awakenings (night-terror-like symptoms), the effects of dreams on daytime mood, the vividness as well as the bizarreness of dreams. These were formed on the basis of our previous clinical and research experience and are subjected to a principal component analysis (see Appendix 2 for the original Hungarian and Appendix 3 for the translated English version). Well-being was measured by a short version (4 items) of the WHO Well-being Questionnaire, the highest quartile/others were categorised for the analysis, the cheerfulness item was analysed separately (not characteristic at all/other answers) (BECH et al. 1996; RÓZSA et al. 2003; SKRABSKI et al. 2005). Self-rated health was measured with the question: ‘How do you rate your health in general?’ There were five responses: very good; good; fair; poor; and very poor. The answers were grouped into poor and very poor/others categories (KOPP et al. 2004; SKRABSKI et al. 2005).

Illness intrusiveness was assessed with the Hungarian version of the Illness Intrusiveness rating Scale (NOVAK et al. 2005).

2.3. Statistical analyses

In order to explore the interrelations between dreaming and health, we conducted a series of Pearson correlations in the case of quasi-continuous dream-specific variables, and a series of logistic regression analyses in the case of dichotomous ones.

Note that due to the large number of subjects (N), almost all reported associations are significant at the level of p < 0.01. In similar cases when interpreting correlational data, the r value in itself needs to be taken into account. Furthermore, since the different calculations of the Pearson correlations are based on a varying number of cases N, we indicate the N’s for every r.