It has happened to all of us at some point. That Friday night with friends that gets out of hand and turns into a sleepless breakfast morning. Now, that we are in the middle of San Fermines, I’m sure it sounds familiar to many… But it may even be the case that we are caught traveling by plane, or with a change in time zone and we spend the entire flight up. Or, putting ourselves in other positions, something unexpected has happened to us and we spend the night without sleeping a wink, either due to a summer heartbreak or an exam that you were carrying with forceps. Be that as it may, when you spend a night without sleep, you can experience a series of effects, both physical and mental, generally of a negative nature: from feeling tired and fatigued the next day, with a scattered mind and slower reactions, feeling severe difficulty concentrating and even noticing changes in your appetite.
But now, a study led by the Perelman School of Medicine at the University of Pennsylvania (Philadelphia) has investigated a seemingly contradictory phenomenon of sleep deprivation leading to improved mood in patients with depressive disorders. Or rather, it has corroborated something that has been studied for decades. And it is that, as they collect in Scientific American, already in 1818, the professor of psychiatry Johann Christian August Heinroth, suggested that sleep deprivation could alleviate melancholy or depression. Although it took years until, in 1959, new research began to emerge suggesting that a sleepless night could improve mood in depression. Subsequent experimental trials in the 1970s confirmed this curious benefit. More recently, a meta-analysis published in 2017 on the antidepressant effects of acute sleep deprivation confirmed that a sleepless night, especially with the lights on, provides mood benefits in about half of people with depression.
In the new article published in PNAS“Enhanced amygdala-cingulum connectivity is associated with improved mood in healthy and depressed individuals after sleep deprivation,” the research team mapped the brain region’s activity via resting-state functional magnetic resonance imaging to see why some people get a healthy boost from a negative public health epidemic.
The study finds that one night of total sleep deprivation improved amygdala connectivity to the anterior cingulate cortex, which correlated with better mood in some healthy and depressed people.
Why a sleepless night can improve your mood
In sleep deprivation experiments conducted in both healthy individuals (n=38) and patients with major depressive disorder (n=30), along with 16 controls allowed uninterrupted sleep, researchers explored the effects of total sleep deprivation (TSD) on mood and functional connectivity networks. The experiments were performed in the Laboratory of the Translational Clinical Research Center of the Hospital of the University of Pennsylvania for five consecutive days. All participants underwent three rs-fMRI scanning sessions. A total of 210 fMRI images were acquired per participant.
Participants underwent three resting-state fMRI sessions over the five days. The first scan occurred after a normal night’s sleep on the morning of the second day for reference. In the TSD groups, participants had their second scanning session in the morning of day three after no sleep.
The participants were then allowed two nights of restful sleep and had their last scanning session on the morning of the fifth day. All participants completed a shortened 37-item version of the Mood Profile every two hours on days two through five.
As expected, most of the participants showed a worsening of mood immediately after losing a night’s sleep. Thirteen of the 30 (43%) depressed participants experienced an improvement in mood, and the remaining 17 participants experienced worsening or no change in mood after one night of DST.
After a restful night’s sleep, 20 participants with major depressive disorder experienced an improvement in mood, and the remaining participants experienced worsening or no change in mood.
Connectivity between the amygdala and the anterior cingulate cortex was significantly increased in patients with improved mood, but less so in those with non-enhanced mood. The amygdala is the core of the fight or flight response, processing fearful or threatening stimuli and sending signals to other parts of the brain for responsive action.
The anterior cingulate cortex (ACC) region of the brain is involved with both the “emotional” limbic system and the “cognitive” prefrontal cortex. Among other things, it plays an important role in the ability to control and manage emotional states or affective regulation.
The findings suggest that amygdala-ACC network connectivity may reflect neural resilience to altered mood after sleep loss and thus may be a potential target for antidepressant interventions.
According to the researchers, a possible explanation for individual differences in the influence of TSDs may lie in the duration of rapid eye movement (REM) sleep.
Major depression has previously been associated with REM sleep abnormalities. Excess REM sleep would decrease norepinephrine, resulting in decreased ɑ-2 receptor binding in the middle frontal lobes composed of the ACC and medial prefrontal cortex. Absence of REM sleep with TSD may give some participants a break to improve top-down control of the amygdala, resulting in an antidepressant effect.
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