Seasonal affective disorder

The weather can affects people mood when it is always dark.

Seasonal affective disorder (SAD), also known as winter depression or winter blues, is a mood disorder in which people who have normal mental health throughout most of the year experience depressive symptoms in the winter or, less frequently, in the summer,^[1] repeatedly, year after year. The US National Library of Medicine notes that “some people experience a serious mood change when the seasons change. They may sleep too much, have little energy, and crave sweets and starchy foods. They may also feel depressed. Though symptoms can be severe, they usually clear up.”^[2] The condition in the summer is often referred to as Reverse Seasonal Affective Disorder, and can also include heightened anxiety.^[3]

There are many different treatments for classic (winter-based) seasonal affective disorder, including light therapies with bright lights, anti-depression medication, ionized-air administration,^[4] cognitive-behavioral therapy, and carefully timed supplementation of the hormone melatonin.

Pathophysiology

Seasonal mood variations are believed to be related to light. An argument for this view is the effectiveness of bright-light therapy.^[5] SAD is measurably present at latitudes in the Arctic region, such as Finland

Treatment

Another type of light therapy lamp

There are many different treatments for classic (winter-based) seasonal affective disorder, including light therapies, medication, ionized-air administration, cognitive-behavioral therapy and carefully timed supplementation of the hormone melatonin.

Bright light treatment using a specially designed lamp, or light box, provides a much more intense illumination than traditional incandescent bulbs are capable of. The light is usually white “full spectrum”, although blue light is also used. The light box has proven to be effective at doses of 2500 - 10,000 lux,^[11] the sufferer sitting a prescribed distance, commonly 30-60?cm, in front of the box with her/his eyes open but not staring at the light source.^[6] Most treatments use 30-60 minute treatments, however this may vary depending on the situation. Many patients use the light box in the morning, and there is evidence that morning light is superior to evening light, although people can respond to evening light as well.^[15] Discovering the best schedule is essential. One study has shown that up to 69% of patients find the treatment inconvenient and as many as 19% stop use because of this.^[6]

Dawn simulation has also proven to be effective; in some studies, there is an 83% better response when compared to other bright light therapy.^[6] When compared in a study to negative air ionization, bright light was proven to be 57.1% effective vs. dawn simulation, 49.5%.^[4] Patients using light therapy can experience improvement during the first week, but increased results are evident when continued throughout several weeks.^[6] Most studies have found it effective without use year round, but rather as a seasonal treatment lasting for several weeks until frequent light exposure is naturally obtained.^[5]

SSRI (selective serotonin reuptake inhibitor) antidepressants have proven effective in treating SAD. Bupropion is also effective as a prophylactic.^[7] Effective antidepressants are fluoxetine, sertraline, or paroxetine.^[5][16] Both fluoxetine and light therapy are 67% effective in treating SAD according to direct head-to-head trials conducted during the 2006 CAN-SAD study.^[17] Subjects using the light therapy protocol showed earlier clinical improvement, generally within one week of beginning the clinical treatment.^[5]

Negative air ionization, involving the release of charged particles into the sleep environment, has also been found effective with a 47.9% improvement.^[4] Depending upon the patient, one treatment (ie. lightbox) may be used in conjunction with another therapy (ie. medication).^[5] Modafinil may be also an effective and well-tolerated treatment in patients with seasonal affective disorder/winter depression.^[18]

Alfred J. Lewy of Oregon Health and Science University in Portland, OHSU, and others see the cause of SAD as a misalignment of the sleep-wake phase contra the period of the body clock, circadian rhythms out of synch, and treat it with melatonin in the afternoon. Correctly timed melatonin administration shifts the rhythms of several hormones en bloc.