According to a study published in the journal Frontiers in Communication, inconsistencies in what individuals say stand out more clearly when they are feeling down or are in a negative mood. The lead author of the study stated that different brain networks appear to assist language and mood in different ways.

The goal of the study was to alter the emotions of the participants by showing them snippets from either a humorous television programme called "Friends" or a depressing film called "Sophie′s Choice." The participants′ emotions, both before and after seeing the video, were assessed using a computerised survey. The researchers discovered that although the humorous videos had no effect on participants′ emotions, the depressing films were successful in making individuals feel more down.

After that, the participants listened to a series of emotionally detached audio recordings of four-sentence tales, each of which featured a "critical sentence" that either supported or contradicted their default, or familiar, word knowledge. The participants′ brain waves were monitored via an EEG test, which monitors brain waves, as that statement was presented on a computer screen one word at a time.

Additionally, the researchers provided versions of the stories in which the crucial words had been switched around such that they no longer made sense in the context of the narrative. For instance, the phrase "With the lights on, you can see less" might be used in the narrative about night-time driving. After that, they examined how the brain responded to the contradictions in relation to mood. Based on the survey responses, scientists discovered that when people were in a bad mood, their brains exhibited a pattern of activity that was strongly related to re-analysis. 

(Source: https://www.tribuneindia.com/news/health/study-explains-how-your-mood-affects-the-way-you-process-language-472728 )