Sleep tight means have a good night's sleep. An article in the Scientific American (2023) asserts that adequate sleep helps regulate emotions. Research strongly supports that better sleep is linked to better emotional health. Those people who have chronic disruptions of their nightly sleep tend to be grumpy at best, and they often have negative feelings even about their ordinary daily experiences.
For decades scientists and medical professionals have believed that sleep problems are symptoms of depression and anxiety. In other words, they thought that the emotional upset came before the sleep loss. But more recent evidence shows that sleep problems can come first and also can interact with emotional disequilibrium with the result that both become worse.
One large-scale study found that chronic sleeplessness went along with a three times greater onset of depression a year later and a twice-fold increase in the onset of anxiety. Insomnia makes at-risk people more likely to develop post-traumatic stress disorder, suicidal behavior, and relapses of formerly treated depression and anxiety. It often proceeds symptoms of bipolar disorder. Even in psychologically healthy people, prolonged sleep loss can result in psychosis; therefore studying it has been deemed unethical.
Neuroscience has found evidence that sleep disturbance can impact the brain's circuitry for regulating emotions. The amygdala is believed to be the seat of our emotions, and the prefrontal cortex regulates it and modulates its emotional expression. The loss of one night's sleep can drastically drop the activity in the prefrontal cortex. The neural activity between the amygdala and prefrontal cortex significantly weakens to the point that the threshold for what the brain perceives as emotional becomes much lower. Less emotional control makes anxiety and depression more likely.
The finding that only one single sleepless night can affect our emotions causes concern. We need to be aware of the close connection between sleep and emotional health. With that awareness we need to be careful to get our needed sleep.
REFERENCE
Simon, E. B. (2023). Sleep sustains emotional health. Scientific American, 329(4), 84-85.