It depends on the severity. Mild depression I can just slog through it and carry on with life. Moderate and I find it hard to get off the couch, socialise and have to drag myself to work. I feel very drained and my mind is much slower than usual. Severe depression and I cannot function, hardly eat or shower, call in sick to work, stay in bed for hours once awake and then get up only to crash on the couch most of the day. I feel dead inside and have SI. My brain hardly works at all. I find no enjoyment from anything, even things I usually love and my concentration is shot. I will surf the net while watching TV and not absorb any of it. My Mum tends to cook for me and do my washing or I wouldn't eat or have clean sheets/clothes. Really bad times I end up IP. Usually for me my depression turns into a mixed state and that is even worse due to agitation, SI, racing thoughts, very low mood and extreme irritability.