Cortisol and Seasonal Changes in Mood and Behavior

Whoever wishes to pursue the science of medicine in a direct manner must first investigate the seasons of the year and what occurs in them." --Hippocrates1 Since ancient times, people have been aware of seasonal changes in mood and behavior.1-3 Poets have described the sense of sadness, loss, and lethargy that can accompany the shortening days of fall and winter.1 Many cultures and religions have winter festivals associated with candles or fire. These festivals represent attempts to raise spirits in a season when the days are short.Historical background The concept of seasonal mood disorders dates back to the dawn of medicine.2,3 Seasonal depressions were described by the Greek physician Hippocrates circa 400 bc.4 About 2000 years ago, the Greek philosopher Posidonius wrote that "melancholy occurs in autumn, whereas mania in summer."5 In the second century, Greco-Roman physicians were treating depression and lethargy with sunlight directed toward the eyes.6,7 In 1894, explorer Frederick Cook linked seasonal loss of sunlight to a mood disorder.8 Cook described a syndrome characterized by a loss of sexual desire and energy, fatigue, and a profoundly depressed mood. The French neurologist Esquirol9 and the German psychiatrist Kraepelin10 both described seasonal changes in mood in books published in the years 1845 and 1921, respectively.Characteristics of seasonal affective disorder In 1984, Rosenthal and associates11 described the syndrome of "seasonal affective disorder" (SAD), a condition in which depression in fall and winter alternates with nondepressed periods in spring and summer. It was suggested that in order for a diagnosis of SAD to be made, the following criteria must be met: a history of a major affective disorder; at least 2 consecutive previous years in which depression developed during fall or winter and remitted by the following spring and summer; absence of any other Axis I psychiatric disorder; and absence of any clear-cut, seasonally changing psychosocial variables that would account for the seasonal variability in mood and behavior.11 Later, an opposite pattern--depression in the summer and nondepressed periods in the winter ("summer SAD")--was described.12 These 2 types of SAD probably represent a subset of a variety of seasonal behavioral disorders. SAD has been included in DSM-III-R and DSM-IV as having a "seasonal pattern," an adjectival modifier of any form of seasonally recurrent mood disorder.13,14 The onset of winter SAD usually occurs between the age of 20 and 30 years, but affected people often do not seek psychiatric help for some time.3,15 Many patients with SAD report disliking winter since their teenage years, although the problem usually becomes severe only in adulthood. Sadness, anxiety, irritability, decreased activity, difficulties at work, social withdrawal, changes in appetite, decreased libido, and changes in sleep are characteristic symptoms of winter SAD.11 Most patients with winter SAD have atypical depressive symptoms such as increased sleep duration, increased appetite, weight gain, and carbohydrate craving. Depressive episodes are generally mild to moderate, but some patients need hospitalization. The neurovegetative symptoms of subsyndromal SAD are similar to those of SAD, but major depression is absent.16 Patients with winter SAD may experience a reversal of their winter symptoms in summer, including mild hypomania; elevated mood; increased libido, social activity, and energy; and decreased sleep requirements, appetite, and weight.3 Most episodes of SAD occur within unipolar major depressive disorder, a substantial minority have accompanying hypomanic episodes (bipolar II disorder), and very few are associated with manic episodes. Patients with summer SAD usually report typical vegetative symptoms such as insomnia and loss of appetite and weight.12 The degree to which season changes affect mood, energy, sleep, appetite, food preference, or desire to socialize with others has been called "seasonality."1,16 Seasonality can manifest in different