Validation and psychometric properties of the Spanish Mood Rhythm Instrument

Mood-related behavioral display a daily rhythmic pattern. However, most clinical instruments do not assess mood rhythm aspects. The Mood Rhythm Instrument (MRhI) intends to contribute to filling this gap. We evaluated the psychometric properties and validated the MRhI in a Spanish sample (N = 457), exploring the relationship with chronotype and social jetlag through the reduced version of the Morningness-Eveningness Questionnaire (rMEQ) and the Munich Chronotype Questionnaire (MCTQ), respectively. The MRhI proved to have adequate internal reliability. Somatic and cognitive variables displayed a higher self-reported frequency of rhythmic pattern than affective variables. Sex differences were only observed for sexual arousal, with females reporting higher rates of rhythmicity. The frequency of self-reported rhythmicity was similar between chronotypes. Chronotype and social jetlag scores correlated with most MRhI variables, though rhythmicity depended primarily on age. This study underlines the importance of assessing mood variability through a reliable and user-friendly instrument that could be useful in cross-cultural studies to further our knowledge on the association among mood symptoms, circadian rhythms, and mental illness.