Rule out medically, first

New, persistent irritability is worth checking medically: **hyperthyroidism**, hypoglycaemia, iron and vitamin D deficiency, sleep apnoea and chronic pain all produce it directly. In women, the premenstrual phase and perimenopause are frequent and often unrecognised causes. Some medications — corticosteroids, some hormonal contraceptives, asthma treatments — list it as a side effect. And chronic sleep deprivation, whatever its cause, produces it on its own, measurably.

What is actually happening

Emotional regulation is a finite resource, and spending it is invisible. A day of decisions, swallowed conflicts and sustained attention empties the tank without anything dramatic happening.

When the tank is empty, the reaction threshold drops. The spilled glass at 7pm isn't the cause — it's the last thing that demanded regulation from a system that had none left. That's why the reaction looks disproportionate: the visible trigger is small, but it isn't what produced it.

The second mechanism is that irritability is frequently a mask. Underneath it, most often, sit exhaustion, anxiety or depression — and in men particularly, depression presents as irritability more often than as sadness, which is one reason it goes underdiagnosed.

What it could be

Several possibilities, because this list is not a diagnosis. What separates them is in the detail below each.

Exhaustion / burnout
How to tell
Irritability rises towards the end of the day and the week, drops after real rest, and comes with the sense of having nothing left to give. By far the most common cause.
Depression
How to tell
The irritability is constant rather than tied to tiredness, and comes with anhedonia and disrupted sleep. In men and adolescents it is frequently the dominant form — more visible than sadness.
Anxiety
How to tell
An already activated nervous system has less reserve for anything else. You'll recognise the pattern if the irritation arrives alongside physical tension, restlessness and difficulty sitting still.
Missing boundaries
How to tell
The outburst follows a run of “yes”es you didn't want to give. Accumulated resentment exits on a minor trigger, usually aimed at whoever is safest — family, not the actual source.

What helps now

Treat the cause, not the moment. Sleep, regular food, alcohol. Most outbursts don't happen to angry people, they happen to exhausted ones, and no breathing exercise compensates for three weeks of insufficient sleep.

Catch the physical signal early. Clenched jaw, raised shoulders, heat in the chest. The window for intervening is there, 30-60 seconds before the peak — not at it.

Leave the room, announcing it. "I need ten minutes, I'll be back." The difference from slamming the door is enormous for the other person: the first is regulation, the second is punishment.

Don't vent. Shouting or hitting something raises later aggression rather than lowering it — the finding has replicated for decades. Rage rooms are entertainment, not treatment.

Keep a log of episodes — what came before, how much you slept, what you didn't say. After ten entries the pattern has two or three recurring triggers, not twenty.

When to get help

Get help if you've become physically aggressive — with objects or people — if those around you calculate your mood before speaking, if it has cost you a relationship or a job, or if you drink to calm down. **If you have hurt someone or fear you might, get help now rather than after the next episode; in immediate danger, call 112.** Anger that reaches violence is not solved with breathing techniques.