So this lecture we'll talk about Mood and Mood Disorder. So what is mood and what is emotion? Sometimes people can confuse these two concepts together. An emotion refers to a state or an event caused by a specific target and it could be very brief in duration, can last only seconds or minutes. And they're usually very, very specific. For example, anger, fear, sadness, or happiness. And usually the emotion comes with the very distinct facial expression. We have very different facial expressions between sadness and happiness, for example. And sometimes the emotion can be action oriented. That means we under certain emotion people plan to do something. The cause of the mood is often very general or sometimes can be unclear and it lasts much longer than the emotion. It can last for hours and days. And compared to the emotion, the mood is more general. It can be positive or it can be negative. And it's generally not indicated by distinct facial expression. So, if you are under some kind of mood, normally you don't have very typical facial expression for that mood. It's cognitive in nature. Meaning, thinking or brooding can affect the mood. So the spectrum of mood and emotion, it can span from the happiness to disgust. And we can clarify the emotion or the mood into positive emotion or positive mood and negative emotion and mood, and mood states generally grouping of this state. And if we look at the sources of emotion and moods, we can see there are several sources. One is the time of the day, or the time of the week. So, statistically, we have the highest positive, the blue line is the positive mood or emotion, or the dark, the black line, is the negative one. So statistically, we have the happiest time during Saturday, and the lowest time happened on Sunday. You have the highest negative emotion and lowest the positive emotion. So maybe people predict the Monday is coming. So the Sunday is the saddest day and Saturday is the happiest day. So other sources other than the time of the day and the week, so the weather, so weather can affect mood a lot. But there's no impact according to a very restricted research. And then there's a stress. There's study saying increase of stress can affect our moods in a social activity and also sleep. Better sleep can help you to have more positive mood and emotion. And the more sources exercises, and people say if you have physical exercises, you have a better mood. The exercises can help you produce more endorphin, which can activate your reward pathway that we'll talk about later in the mood disorder section. And age, so older people experience more, express negative emotion less frequently. So older people are happy people. Gender, women show more emotional expression. Women experience emotion more intensely than men and display more frequently expression of emotion.