The aim of this study is to analyze both depressive symptomatology and psychological well-being fluctuation in a day-to-day basis in the general population, in order to identify contextual determinants of the mood and well-being changes

Introduction: The Experience Sampling Method is a research tool to study what people do and feel in their day to day. It allows to analyse temporal relationships between variables and has a high ecological validity.

Aim: To evaluate fluctuations of depressive symptoms and subjective well-being and to analyse the factors related to these fluctuations.

Methodology: Longitudinal study that will follow up for two weeks a representative sample of the population aged 18 to 65 years living in Madrid using the Experience Sampling Method. An interviewer will visit the participants at their home to carry out a structured interview on mental health and well-being and to install a mobile app on the smart phone of participants in order for them to fill out information about their emotional state during the following two weeks. Participants will use the smart phone screen to fill out a brief questionnaire about their feelings, the activities they are doing and the people with whom they are interacting. Multilevel analysis based on lineal hierarchical models will be employed for data analysis as well as methods based on machine learning.

Inclusion Criteria:

• 18-65 years old
• Non-institutionalized resident in Madrid
• To own a smart phone

Exclusion Criteria:

• To present noticeable cognitive or other limitations that impede following the interview

Residents of Madrid, Spain.