Dysfunctional beliefs about negative emotions are associated with symptoms such as anxiety, depression, fatigue, fear of negative evaluation, less search for social support and emotional suppression. Emotional suppression is a counterproductive emotion regulation strategy related to difficulties such as lower levels of understanding and greater undesirable emotional states. Unhelpful beliefs are also related to different clinical conditions, and may also come from environmental factors. These beliefs act as a risk factor and vulnerability for certain groups, leading to higher rates of symptoms, emotional dysregulation and stress. The first study addressed participants exposed to such environmental stressors, namely military policemen. To investigate mental health data in this population, participants were assessed for beliefs about emotions, anxiety, depression, fatigue and fear of negative assessment. Results indicates high scores in the scales for fatigue, depression and anxiety, with high prevalence rates of these same symptoms in the at-risk group. To the best of out knowlwdge, this is the first time that fatigue prevalence rates are described in the literature. Considering what has been exposed so far, it is possible to suggest programs for policemen that address mental health, especially interventions that contemplate emotion regulation. The second study sought to validate the Emotion Regulation Questionnaire for the Brazilian adult population, investigating the relationship between emotion regulation strategies, beliefs about emotions and alexithymia. The results point to a correlation between the mentioned clinical variables, albeit with a more subtle influence than expected in the first study. Furthermore, suppression is a strategy that deserves greater attention due to the high association with variables present in different clinical groups and with emotional difficulties, such as alexithymia and high levels of unhelpful beliefs. Emotional suppression was shown to be a non adaptative emotion regulation strategy, presenting correlations with high levels of beliefs about emotions and alexithymia. Considering the present results as well as the existing literature, emotional suppression should be adressed in future clinical trials. In addition, this is the first time that the relation between beliefs about emotions and alexithymia is observed and that the psychometic properties of the Emotion Regulation Questionnaire are investigated in adult population. Thus, in general, results points to a correlation between the clinical variables cited above, with a more subtle influence of beliefs about emotions in the first study, but in both with associations that point to the dysfunctional nature of these beliefs, by presenting associations with high levels of depression, fear of negative evaluation, emotional suppression and alexithymia.