It's more than happy / sad cycles
Biorhythms are important for a number of biological functions. They impact us in many ways with both daily (circadian) and annual (circannual rhythms).
We have had some success moving away from the traditional happy/ sad description of bipolar and instead describing the cycles in terms of feeling "fast" or "slow". Do you feel you may have bipolar disorder? Take our "fast"/"slow" test to see how your clock is running. Start a stop watch. Put it face down and go about your business. After some period of time try to "guess" how much time has passed. Then compare it to the amount of time that has passed on the stopwatch. People in the slow phase of the disorder
tend to say less time has passed. People in the fast phase tend to say more time has passed.
A BETTER EXPLANATION:
Why does everyone seem to have bipolar disorder? It seems like the diagnosis du jour and suddenly everyone has some form of cycling mood disorder. There are three possible explanations and they are not mutually exclusive.
1. Bipolar disorder is over diagnosed: As something becomes popular. As it becomes more well known. It becomes easier to see and some people start to see it everywhere. There certainly is some of this going on with bipolar disorder. We see many patients who have.
2. Bipolar disorder has been under diagnosed in the past.
3. The environment is changing to cause more bipolar disorder.
Bipolar Disorder is traditionally defined as cycles of elevation in mood and activity (mania) and significant periods of inactivity and decreased mood hence the term "bipolar" or two opposite poles of mood. Reasons for this have often been described as a chemical imbalance. I have found this answer to be somewhat unsatisfying and instead feel an evolutionary model more accurately explains what is occurring. We base our treatment approach on this theoretical model using empirical research as well. There is more going on than happiness and sadness. I think it is better understood as a "clock disorder" as opposed to a "mood disorder". In fact, the
condition has been linked to annual and daily rhythms in the following articles:
(Bipolar patients always feel out of sorts with the world. They are "up" when the world is sleeping and hibernating when the world is going. They feel warm and flushed at times during the evening (signifying their body temperature is elevated because they "feel" like they should be awake. They feel inert and lethargic at times during the day. (Like their body wants to sleep.)
Treating their disorder as a clock disorder makes them keep stricter day/night cycles (bright light activity in day....darkness and slowing down at night.)
Bipolar disorder tends to occur in those with some Northern Ancestry. It also has been shown to have a genetic link to Seasonal Affective Disorder. SAD is described as a subtype of affective disorder (mood disorder) with a seasonal pattern usually in the winter when sufferers experience clinical depression and has a greater prevalence in countries with greater northern latitude. (Reference to SAD)
One possible evolutionary explanation is the bipolar disorder is an adaption to living in areas with harsh winters. Individuals get very active or "manic" during the summer when light is plentiful and the environment is more forgiving. They then enter a state of inactivity or hibernation in the winter to conserve calories and save themselves from too much exposure to a harsh winter. They then reenter hyperactivity when the weather lightens to get everything done they need to get done.
How could that effect people living in Florida where we don't have very harsh winters? Why do some people cycle throughout the year?
The secret is in the light. Here is some research linking bipolar to disturbances in light processing and some common mood stabilizers and how they effect light and melatonin.
Seasonal rhythms are predominantly determined by length of sunlight not temperature. In other words as the length of day shortens and lengthens our bodies feel we are different periods of the year.
Two periods in our experience that naturally seem to be present.
Around Sept-November seems to be a period of depression Around April- Sept seems to be a period of mania and also anxiety. Now we would expect this anxiety to be associated with fear over the coming winter. In fact the period after the Summer Solstice (June 21st) is associated with a high violent crime rate see below:
And in fact suicide rates are relatively low around Christmas (see below). (May has the highest suicide rate)
What about other cycling?
Well we live in a world where we can control light exposure but room light is very different from natural sunlight so our bodies read it differently. And this possibly accounts for all the weird cycling we see. For instance, look at this research below that shows a seasonal variation in depression markers. What this means is that if you get the season wrong...you may get depressed. How do you get the season wrong? By having confusing light cues that make your body think it's a bad time of year.