Depression is one of the most commonly diagnosed mental disorders in the United States (as well we the developing world).
And for every person who’s handed a clinical diagnosis for depression, an estimated 1-2 additional people suffer from the debilitating disease in silence.
Over the past few years, as the focus on mental health becomes a larger part of mainstream medicine, the discoveries about what causes depression have multiplied.
We know the underlying, physiological causes of depression, mainly that imbalances in neurotransmitters can lead to feelings of depression.
But, we’re still learning a lot about what leads to those problematic imbalances in the first place.
A recent study conducted by researchers at the University of Boulder and the Channing Division of Network Medicine at Brigham and Women’s Hospital in Boston, MA has made a telling discovery showing a link between what time individuals fall asleep and wake up and their overall risk for developing depression.
And what you might find surprising is just how significant the link is.
To come to their conclusions the researchers poured over data collected from one of the comprehensive health studies ever conducted, the Nurses’ Health Study II.
The data they were interested in the most had to do with what time subjects went to sleep and woke up.
And from that data, they discovered that sleep patterns have a dramatic effect on neurochemistry.
From a sample of 32,470 female participants, aged 55 on average, all who were depression-free at the beginning of the study, they found that a late bedtime an a late wake time increased the chances a person would develop depression.
At the beginning of the data-set, none of the women providing information were depressed.
At the end of the data-set, (roughly 2 years in time), a statistically significant number reporting feeling depressed.
To see what may have caused this they looked at the study participants’ sleep habits.
They broke the participants up into 3 groups.
Early birds: those who went to bed early and got up early.
And intermediate sleepers: Those who had a combination of both sleeping patterns.
To make sure their analysis wasn’t tainted by factors unrelated to sleep, the researchers controlled for “the impact of environmental factors, such as exposure to light and work schedule, on a person’s sleep-wake cycle. Other risk factors for depression — including weight, level of physical activity, existing chronic diseases, and sleep duration”
What they found was the early risers were far less likely to develop depression over time than those going to bed late and getting up late.
Their research indicated that early birds had a 12–27 percent lower risk of depression than “intermediate type” participants.
And the night owls had it even worse.
They were 6% more likely to develop depression than “intermediate types.”
At first blush, this research doesn’t really make sense.
But one thing the researchers noted was that many times, people who go to bed late, are more likely to live alone and also don’t have the same kinds of healthy relationships as those who go to bed early and wake up early.
Early-birds were typically married or in a significant relationship, and had other healthy relationships. Conditions that other research shows to have strong correlations with better mental health.
Likewise, the researchers didn’t conclude that night owl behavior would cause depression either.