Explain why can lack of sleep cause mood swings?

Neurological effects of sleep deprivation on mood

When you lack sleep, your brain struggles to properly regulate emotions. Certain parts of the brain, like the amygdala, become hyper-reactive. The result: you react more quickly and intensely to negative or frustrating things. At the same time, your prefrontal cortex, which is supposed to calm things down and control your impulses, doesn’t work as well. So, this leads to an emotional short circuit: irritability, sadness, or even heightened sensitivity over trivial matters. Your mood then goes on a roller coaster, just because your neurons are tired and not communicating well with each other.

Impact on the production and regulation of emotional hormones

Sleeping less directly influences our hormones, particularly serotonin and cortisol. When you're tired, the production of serotonin, that little molecule that helps stabilize your mood, gets disrupted. As a result, your morale goes on a rollercoaster. On top of that, your body releases more cortisol, the stress hormone, when you're lacking sleep. And too much cortisol is not cool: it makes you anxious, irritable, or even downright grumpy. Regular sleep helps the body regulate all of this, and as soon as there's a delay, it's the hormonal balance that suffers.

Relationship between sleep deprivation and increased irritability

As soon as we sleep less, our brain becomes more sensitive to stressful situations and reacts more strongly to anything that irritates it. Even mild sleep deprivation alters the amygdala, a small area of the brain responsible for our quick emotional responses. The result: less patience, more susceptibility, and a tendency to blow up over trivial matters. And when fatigue accumulates, the ability to filter and manage the small annoyances of everyday life decreases significantly, making it more common to shift from a calm state to sudden bouts of irritability.

Alteration of stress management and negative emotions

When we lack sleep, the brain becomes less adept at managing stressful situations. The prefrontal cortex, which normally acts as the command center for our emotions, quickly becomes overwhelmed and loses its effectiveness. We then easily find ourselves overwhelmed by negative emotions such as anxiety or sadness. Even small annoyances can seem very difficult to handle. Furthermore, lack of sleep increases the production of cortisol, the stress hormone. More cortisol often means more inner tension, less patience, and, overall, a reduced ability to calmly cope with daily challenges.

Social consequences of lack of sleep on behavior and relationships

Our mood depends a lot on sleep, and when we sleep poorly, we easily become irritable or impatient with those around us. This often leads to unnecessary little arguments or misunderstandings. We listen less to others, communicate poorly, and our empathy declines. It's normal, because when we're tired, we perceive everything that others say or do in a much more negative light. Over time, this makes family, friendship, or professional relationships quite tense, sometimes leading to gradual isolation or recurring conflicts.