Lewy et al (2006) study review
This study was based by another study done by Avery et al. (2001). The study investigated the relationship of melatonin levels in conjunction with sleep patterns and Seasonal Affective Disorder. Seasonal Affective Disorder is a type of depression that occurs in the beginning and ending stages of winter, where the amount of daylight is shorter. This usually occurs in northern countries with colder climates, since the production of melatonin is triggered by lack of light.
The purpose of this study was to investigate the relationships between melatonin, the sleep cycle, and the time of melatonin release.
The researchers conducted an experiment similar to Avery (2001). Participants with Seasonal Affective disorder (SAD) was divided into four groups-- dawn simulation therapy, traditional bright-light therapy, a control and a group given with low doses of melatonin at night.
The researchers found that the sleep patterns and mood of the participants were significantly higher than the other groups, but not high enough to compare with the group receiving bright-light therapy. Therefore, it can be concluded that the bright-light therapy is more efficient in treating Seasonal Affective disorder (SAD) than the other procedures (dawn simulation, group given low doses of melatonin at night.
This study contributed to the understanding of the relationship between melatonin and the circadian rhythm (sleep-wake cycle). This can also be applied to the concept of jet-lag, in which our bodies can adapt to another time zone by making us sleep at specific times.
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