An idiom or a four-word phrase can also be used to describe one's mental state.

An idiom or four-word phrase to describe being in a bad state of mind could be: 1. Mental exhaustion: It refers to mental exhaustion and lack of physical strength. 2. Dispirited: It refers to a person who is in a bad mental state and is listless. 3. Insomniac anxiety: It refers to a person who is in a poor mental state and often suffers from insomnia or anxiety. 4. listless: It refers to a person's poor mental state, lack of vitality and enthusiasm. Exhausted: It refers to a person who is in a bad mental state and feels very tired. 6. Decadence: It refers to a person's poor mental state and loss of positive attitude and motivation. 7. Being absent-minded: It refers to a person who is in a bad mental state, unable to concentrate on his studies or life, and is somewhat light-headed. 8. Mental and physical exhaustion: It refers to a person's mental state being poor and feeling haggard and devoid of energy.