As many parents can attest, a sleepless night doesn’t make for a happier morning. This is why it is not surprising that complete sleep deprivation temporarily restores the mood of almost half of people with major depressive disorder.
Brain scans of volunteers have shown why this might be the case, revealing dramatic changes between critical brain regions in healthy volunteers and those diagnosed with severe depression.
A study led by the University of Pennsylvania in the US used functional MRI to map and measure the brain activity of 54 people with no history of mental illness or mood disorders and 30 with major depression.
Of those without a history of depression, 16 were placed in the control group and given a good night’s sleep between trials. For everyone else, without a diagnosis, it was one long night of reading, playing computer games, watching television… and not shutting down. No caffeine, no exercise. Staying quiet until sunrise.
When robbed of enough time to rest and recharge, the human brain is not the most efficient machine. Many muscles in the front of our brain called the dorsolateral prefrontal cortex chug slowly, which makes it difficult to listen.
Not only is our awareness reduced, but also our ability to control our emotions since the amygdala – the main part of the limbic system – works overtime, especially in response to negative situations. Without the prefrontal cortex to temper our emotions, we can become restless and angry.
However, since the beginning of psychiatric research, sleep deprivation has been seen as a way to reduce stress, especially in people with anxiety disorders.
Indeed, recent researchers observed an improvement in 13 out of 30 patients with major depression after a night’s sleep.
Meanwhile, the psychological test results of people without depression often show the type of fatigue that is more common when they are sleep deprived.
Photographs revealed a possible reason for this difference. The connection between the amygdala and the bridge between the emotional and mental parts of the brain called the anterior cingulate cortex seemed to increase in those whose moods were said to be improving, regardless of their mental health.
Even after two sleepless nights, this connection to the two regions remained strong.
Known as chronotherapeutics, the concept of treating mental illness through changes in biological clocks has become an area of great study, meaning that the disruption of our body clocks can, in some ways, restore the processes that have gone awry.
This is not to say that not getting enough sleep at night is a good idea for everyone, it is sleep disorders that are associated with a higher risk of dementia later in life. Getting out of touch with the body clock can wreak havoc on our health, our lives, and our workday.
Mapping major changes in connectivity between brain regions known to be involved in emotional regulation and cognition after sleep deprivation may be another way to establish mechanisms that may underlie other depressive disorders.
The World Health Organization lists major depression as the third most common disease in the world. Knowing that it is possible to improve communication between the areas of the brain that most need to be entertained, one day we may find a way to raise the mood of millions without robbing our brain of the benefits of a good night’s rest.
This study was published in PNAS.