Question: Dr. Dobson, I tend to feel depressed after every holiday, but I don't know why. These special days are very happy ones for my family. Why do I find myself "blue" after such enjoyable occasions?
Answer: It will be helpful for you to understand the nature of emotional rhythm in human beings. Anything producing an extreme "high" will set the stage for a later "low," and vice versa. A few years ago, for example, my wife and I bought a newer home. We had waited several years to find the right house, and we became very excited when escrow closed and the property was finally ours. The elation lasted for several days, during which time I discussed the experience with Shirley. I mentioned that we had been very high and that our excitement could not continue indefinitely. Emotions don't operate at maximum velocity for very long. More important, it was likely that our mental set would drop below sea level within a short period of time. As expected, we both experienced a vague letdown into mild depression about three days later. The house didn't seem so wonderful and there wasn't anything worth much enthusiasm. However, having anticipated the "downer," we recognized and accepted its temporary fluctuation when it came.
Depression therefore should be understood as a relatively predictable occurrence. It is likely to appear, as in your case, following a busy holiday or after the birth of a baby, a job promotion, or even after a restful vacation. The cause for this phenomenon is partly physical in nature. Elation consumes greater quantities of body energy, since all systems are operating at an accelerated rate. The necessary consequence of this pace is fatigue and exhaustion, bringing with it a more depressed state. Thus, highs must be followed by lows. The system is governed by a psychological law. You can depend on it. But in the healthy individual, fortunately, lows eventually give way to highs, too.
From Dr. Dobson's book, Dr. Dobson Answers Your Questions.