- Difficulty concentrating, remembering details, and making decisions
- Fatigue and decreased energy
- Feelings of guilt, worthlessness, and/or helplessness
- Feelings of hopelessness and/or pessimism
- Insomnia, early-morning wakefulness, or excessive sleeping
- Irritability, restlessness
- Loss of interest in activities or hobbies once pleasurable, including sex
- Overeating or appetite loss
- Persistent aches or pains, headaches, cramps, or digestive problems that do not ease even with treatment
- Persistent sad, anxious, or "empty" feelings
- Thoughts of suicide, suicide attempts
Personally I have periods of good mood and high motivation in which I still lack the fundamental energy to do stuff. It's also important to realise that many 'symptoms' of depression would only occur with awful levels of Serotonin that would have dominantly psychological symptoms. It's also important to understand that many people diagnosed with depression wrongly have serious hormonal issues causing the problem and are not in fact suffering clinical depression but situational depression (the two are different).