Depression and the Seasons

There’s a certain slant of light

On winter afternoons,

That oppresses, like the weight

Of cathedral tunes.

Heavenly hurt it gives us;

We can find no scar,

But internal difference

Where the meanings are.                                                                         

         -Emily Dickinson 

            Clinical depression is a complex mental disorder that plagues nearly 20% of the US population every year. This disorder can be characterized by a range of symptoms including noticeably deteriorated mood, severely altered sleep cycles, extreme loss or gain of appetite, and loss of concentration or interest in things that once were pleasurable etc, for a period of two weeks or more (1). Depression is often hard to identify medically because of the qualitative nature of the disorder-- It is difficult to quantify mood deterioration. Specific types of depression are also subject of much debate in the medical community, and although these types of depression may be caused by different factors, they are still just as difficult to diagnose and treat as an average clinically depressed patient.

The supposed causes of depression are numerous, and can include—but are not limited to— genetic factors, environments, and chemical imbalances (2). One study shows that a gene located on ____ is linked to depression and can potentially be inherited. Many studies show that depression can run in families and this gene’s discovery could lead to a more solid explanation of this phenomenon (6). Environment is believed to affect depression too. Severely traumatizing events or stressful life experiences are thought to induce depressive states, although it is unclear as to how and why these experiences affect certain people the way they do (1). Chemical imbalances of specific neurotransmitters are also shown to be strongly associated with depression (5). Although many causes can be attributed to depression, one single cause cannot be solely identified as the sole source of this disorder (1)

            Because the cause for depression has not been yet pinpointed and because depression affects every patient differently, treatments can vary. Psychotherapy can be useful in the diagnosis process of depressed patients (1). Drug treatments are also common. Many prescription drugs created to treat depression today aim to target one specific neurotransmitter that is strongly linked to depression in clinical studies. Drugs like Cymbalta® target an imbalance in serotonin (4), which is known to control many different functions in the body including appetite, sleep, and mood (5). Such drugs have been shown to be extremely effective for some, but useless to others (1).  

           To account for the variable nature of depression from patient to patient, some physicicans have found it useful to classify certain sub-types of depression (1). A specific type of depression is of particular interest because it seems to be affected by more than just genes, environment, and serotonin levels. SAD, or Seasonal Affective Disorder, is a depression that is affected mainly by the changing of seasons and the amount of light received by an individual during certain months of the year. Characterized by symptoms of depression, SAD can cause serious mood changes, and in sever cases, suicidal tendencies (3).

            How does daylight affect mood? When light enters the retina, a nerve impulse shoots through to the hypothalamus, which in turn triggers the pineal gland, which in turn controls the release of melatonin (3). Melatonin is a chemical that is strongly linked to our body’s circadian rhythm function. This chemical has a sedative quality to it, and is normally released in the nighttime to aid in the natural cycle (7). When our eyes perceive daylight, the release of melatonin should stop and resume only when night falls again. When melatonin is released during our waking hours, a depressed mood is likely to follow. This goes far to explain why people in higher altitudes suffer more from this disorder—because their daylight hours can be limited during the long winter months (3).

            This particular type of depression is interesting in that drugs commonly used to treat depression, like Cymbalta®, are effective, but more so with the supplement of light therapy (8). Light therapy consists of light boxes or light panels set up in offices or homes, and with extended exposure, patients report relief from their symptoms. Light therapy has been shown to counteract the negative effects of raised melatonin levels in the daytime and therefore be a viable and affordable means of treatment for many that suffer from this disorder (3).

            There is much dispute over both the diagnosis and treatment of SAD as well as clinical depression (1). Studies of SAD have been complicated and inconclusive because of the lack of research done on this particular disorder (8). Studies of depression are becoming more and more numerous, but researchers still have trouble pin pointing its main cause. Until concise causes of depression can be identified for both depression, and specific types of depression like SAD, treatments will continue to vary and be of experimental nature (1).

1.  The Neurobiology of Depression

2.  All About Depression

3.  SAD: Light Makes Right

4.  How Cymbalta Works

5.  Serotonin: A Molecule of Happiness

6.  Manic Depression Gene Tied to Chromosome 11

7.  Melatonin

8.  Seasonal Affective Disorder