Since I am not a physician, I will not attempt to detail this area. Another aspect of the physical cycle may be diet. One may eat healthy foods and feel good for a while, but then go on a sweets binge that causes an immediate high. Therefore, the result is mood swings from one extreme to the other. Exercise may also play a role in the physical cycle.
Some people go from one extreme to the other concerning exercise.
They may go all out for exercise for a while given them a lift. However, they over do it or get bored. They withdraw from most all exercise and feel a letdown. It should be noted that even after the other areas are covered, there may be a sight lag in the physical. The body may need time to catch up with the thoughts.