A study published in the journal Archives of General Psychiatry found that people suffering from SAD secreted the hormone melatonin for longer periods during winter nights than during summer months. Normally, human production of melatonin, which regulates sleep and is called the hormone of darkness, does not vary with the seasons. Melatonin is what makes us sleepy, and is a natural “depressant.” But, when we have too much of it coursing in our veins throughout the winter, which can happen as temperatures drop and daylight hours go down, varying levels of depression are the result — the SAD symptoms.
As many as 20% of us can suffer from mental symptoms as a result of seasonal change. But, independent of light changes and temperature changes, a recent study has indicated that our brain actually changes with the seasons. Researchers kept participants in a controlled lab both during winter and summer months with no changes in light or temperature, and studied brain activity. During the winter months, brain activity involved in sustained attention was at its lowest. Conversely, working memory and recall was higher during fall and winter months.
Implications for your workforce? When it gets cold outside, don’t expect people to be able to pay attention as well to a task for long stretches of time. But, the fact that memory and recall are better during this time of year might make for a great Training Course season!
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