After a sleepless night, you may be more irritable, short-tempered, and vulnerable to stress. Once you sleep well, your mood often returns to normal. Studies have shown that even partial sleep deprivation has a significant effect on mood.
Studies show people who are sleep deprived report increases in negative moods (anger, frustration, irritability, sadness) and decreases in positive moods. And sleeplessness is often a symptom of mood disorders, such as depression and anxiety.