My friend here has manic depression, also known as Bipolar disorder, dealing with this can be difficult so it is important for his friends and family to be supportive
One of the best things a friend or family member can do is try to be understanding and sympathetic. Bipolar Disorder is unpredictable and offering your support at all times can make a world of difference.
I know you haven't been having a great day today, just remember if you are confused or want to talk about something you can always come to me! Im happy to help.
Due to the unpredictable mood swings of Bipolar disorder, it is always important to help them prepare themselves or prepare yourself in case of one of these intense mood swings, this can include medication, ways of dealing with these episodes and access to help.