There are several hidden signs of depression that may not be easily noticeable. These signs can vary from person to person, but some common hidden signs of depression include: 1. Fatigue or low energy: People with depression often feel constant fatigue and lack the energy to engage in daily activities. They may feel physically and mentally exhausted, even after a full night's sleep. 2. Irritability or anger: While depression is often associated with sadness, it can also manifest as increased irritability or anger.