According to the famous hadith, one of the seven who will be shaded by Allah when there is no shade on the Day of Judgment is he who remembers Allah in private and his eyes well up with tears.
What state is this? Is it sadness? Or happiness? Or something else entirely?
There are states and emotions like this that are not studied or contained in secular disciplines like psychology but are elaborated on at length in the Islamic spiritual sciences.
For example, what is the sweetness of iman? What does tasting it entail? What does it mean to have a soft heart?
These are things that only believers experience and they are gifts granted by the Almighty. They are not reducible to the standard set of basic emotions psychologists identify: happiness, sadness, fear, anger, surprise and disgust.
May Allah purify and soften our hearts!