Winter depression or seasonal affective disorder

Winter depression or seasonal affective disorder

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The following article will distinguish between seasonal affective disorder or winter depression and endogenous depression.

Depression is a heterogeneous disorder in which different types of circadian disorders have been established, while in other patients none could be demonstrated. This diversity reflects that depression can have multiple origins.

Thus, some of which may be associated with circadian dysfunctions and in others not, without knowing with certainty in the first case if the circadian disorder is a symptom or is involved in the etiology or pathophysiology.

All this shows the need to carry out studies in homogeneous populations of depressants so that the results are extrapolated.


  • 1 Winter depression: curiosities
  • 2 Treatment of winter depression by phototherapy
  • 3 References

Winter depression: curiosities

The total incidence of depressive disorders increases considerably in spring and to a lesser extent in autumn. Nevertheless, Patients with this type of disorder have depression in winter and late autumn.

In addition, they improve considerably with the arrival of spring, This pattern cannot be explained by seasonal psychosocial stressors. Numerous studies show that a significant proportion of the population is influenced in their mood by seasonal changes.

The majority of patients with winter depression are women (60-90%), the onset of the disease occurring typically over 30 years. Age is a powerful predictor, Younger people have a higher risk of winter depressive episodes.

The duration of depressive episodes is usually in an average of 5 months, usually beginning in the months of October or November and ending in March or April.

In the first studies it was reported that most of the patients had symptoms of hypomania in the spring and summer months, presenting diagnoses of major depression with hypomania (bipolar II).

Some symptoms in seasonal affective disorder

It is currently unclear whether the seasonal pattern predominates in unipolar or bipolar, although it is clear that among the latter, bipolar type II predominates. As for vegetative symptoms, it occurs:

  • Hyperphagia with increased carbohydrate specific hunger
  • Weight gain
  • Fatigue
  • Premester Changes
  • Substantial increase in total sleep duration and increase in sleep latency
  • Decreased sexual appetite
  • Difficulties at work
  • Withdrawal from social situations

Differences with respect to endogenous depression

Unlike endogenous depressants:

  • The REM sleep latency it is not altered
  • The answer to cortisol suppression test by administration of dexamethasone is similar to that obtained in the normal population
  • Numerous hormonal secretions altered in endogenous depressants remain at normal levels in these patients

The defining characteristic of this type of depression is its reactivity to environmental light and climate changes.. Patients who have traveled or lived in different latitudes show a relief in your symptoms when approaching the equator.

On the contrary, they show a increase in the duration and intensity of their depressive episodes the farther north they were. The reduction in ambient light for any reason, for example, a streak of cloudy weather in summer or a change in the workplace associated with lighting changes, often lead to deterioration in affective states.

On the other hand, the presence of sunny days in summer may predispose to the emergence of hypomanic symptoms. Therefore, it has been suggested that the prevalence of the disorder could vary depending on latitude, with a higher incidence in the northern latitudes.

Theoretical models explaining winter depression or seasonal affective disorder

One of the first theoretical models to explain winter depression has been the control exercised by the light period over the Reproductive behavior in rodents and other species.

These animals have a critical photosensitive interval of 12 hours centered around noon. When the days are shortened in winter, the extremes of that period are not stimulated, producing gonadal regression.

While lengthening the days in summer induces reproductive behavior by stimulating these extremes. These effects are mediated by pineal melatonin.

Both light manipulations and the duration of the nocturnal increase in melatonin can induce regression or gonadal development regardless of the season of the year in which they are performed.

Thus, Winter depression could be reminiscent of the seasonal rhythms of behavior present in animals. Rhythms that are adaptive, making births occur when outside conditions are more favorable for survival.

In this sense, patients with winter depression have a different conception pattern which predominates in the general population. While in the latter the highest month in conceptions is December, Among winter depressives the peak of conceptions appears in the summer months.

Treatment of winter depression by phototherapy

Following the previous model, the light treatment of these patients would consist in increasing the length of their luminous period. Rosenthal et al. (1985), cit. in Del Paso, G. (1998) increased this period three hours before dawn and three hours after dark for two weeks. For this they used intense light in the experimental group and low intensity light in the control group.

The results were spectacular, producing antidepressant effects (measured by the Hamilton depression scale) from 2 to 4 days after the start of treatment.

After its withdrawal there was a relapse from the following 4 days, although it takes about two weeks to return to baseline levels. The control condition produced no apparent response.

Numerous studies have replicated these antidepressant effects of intense light treatment in winter depressives. However, there is a disagreement about whether time exposure to light is important or not (exposure in the morning, in the evening or both together).

Comments about treatment

Patients with winter depression have abnormally delayed circadian phases. In this way, the most noticeable symptom is a hypersomnia associated with a later awakening or alert time.

If this is so, The treatment should consist of exposure to light during the morning. It seems that it is during this period when its exposure produces advance effects on circadian rhythms, which could correct the abnormal phase delays of these patients.

In summary, Exposure in the morning is the one that significantly reduces depression levels. Review studies on the effects of artificial light in the treatment of winter depression conclude that intense light, with at least two hours of daily exposure in the morning over a period of one week is the procedure that results in more clinical remissions .

Another conclusion of this review is that the late-morning joint exposure does not produce more benefit than the morning only exposure. Light exposure from 6 to 8 a.m. It results in a decline in melatonin levels that reaches low levels of the day in two hours.


Calil, H. M., Hachul, D. M., Juruena, M. F., Crespin, J. L., & Nogueira Pires, M. L. (2000). Evaluation of seasonal alterations in humor and behavior in the city of San Pablo.Acta Psiquiatr Psicol Am Lat46(2), 109-18.

Del Paso, G. (1998). A review of the role of circadian alterations in depression. Journal of general and applied psychology: Journal of the Spanish Federation of Psychological Associations51(2), 247-268.

Gatón Moreno, M. A., González Torres, M. Á., & Gaviria, M. (2015). Seasonal affective disorders, "winter blues".Journal of the Spanish Association of Neuropsychiatry35(126), 367-380.

Ivanovic-Zuvic, F., De La Vega, R., Ivanovic-Zuvic, N., & Renteria, P. (2005). Affective diseases and solar activity.Proceedings Esp Psiquiatr33(1), 7-12.

Sciolla, A., & Lolas, F. (1993). Phototherapy and etiopathogenesis of seasonal affective disorder. Topics in affective diseases. Santiago de Chile, Ed. Society of Neurology, Psychiatry and Neurosurgery, 217-26.

Valdez, P., Pérez, J. C., Galarza, J., & Ramírez, A. (1986). Circadian and Ultradian rhythms in depression. Mexican magazine of Behavior Analysis12(2), 137-145.

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