I've noticed this too, I don't think this is specific for people with a depression though. If I have about 4/5 hours of sleep I will be less smart the next day,

I've noticed this too, I don't think this is specific for people with a depression though. If I have about 4/5 hours of sleep I will be less smart the next day, but engaging with others or completing tasks despite the tiredness results in a huge boost to mood and a feeling of exhilaration and happiness. That is not to say you don't feel tired, especially when the work has not yet been completed, and the day is just starting. YMMV, N=1 and all that...