Like times when you have a wild assortment of ideas. Then there are other days, weeks, and months were you don't want to get out of bed. One manic depression symptom is evidenced by the inability to sleep. Another is that you begin to notice that you can become irritable almost without provocation, and you don't think anyone is listening to your great, if not somewhat far fetched, ideas.
If you are prone to starting many projects and unable to complete any of them, and then seemingly out of the blue you are apathetic to those same projects, you maybe experiencing a manic depression symptom. Manic depression symptoms are triggered by an imbalance of the chemicals in your brain that keep you from over or under reacting. During a manic phase, which can last weeks and even years, you are highly functioning in your job, especially if you are in the position to delegate.
This is very important to know, because as we've said, completing the projects yourself can get difficult. Not because you don't want to, but because the ideas are coming so fast that you can't keep up with them. You are the life of the party and enjoy going out and probably spend a lot of money. Then comes the crash. The depression side takes over and all of a sudden you don't feel like doing anything.
Jobs are lost, apathy abounds, and life has no meaning. You may even consider suicide, but even you couldn't really say as to why. This is a manic depression symptom as well. Unfortunately, because the two sides of the illness often don't show themselves within weeks and so go largely undiagnosed as the actual illness. You may see your doctor regarding the sleeplessness during a manic episode, but don't know that the depression episodes are part of the same illness.
Without complete information, most cases go misdiagnosed.