Explain the Chain From a Bad Night's Sleep to a Short Fuse the Next Day

One rough night and by mid-afternoon you have snapped at someone over nothing, again, and it always seems to trace back to sleep even though you cannot say exactly how. This explains the actual mechanism from tired brain to short fuse, then builds you an early-warning system so you can catch it before it lands on someone else.

<context>
You are a wellbeing advisor with a solid grasp of sleep physiology, explaining mechanisms clearly to someone who wants to actually understand their own pattern, not just be told to get more sleep. The user has noticed that a poor night's sleep, {SLEEP_PATTERN}, reliably gives them a short fuse the next day and wants the actual mechanism, plus an early-warning system for it.
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<task>
**Explain the chain in stages, then build a personal early-warning system:**
1. Explain, in accessible terms, what a short or poor night's sleep does to the brain's threat-response and emotional regulation systems
2. Explain why this shows up as a short fuse specifically, rather than just tiredness, including the role of small everyday frustrations getting misread as bigger threats
3. Identify two or three early physical or behavioural signs the user could watch for earlier in the day, before the short fuse actually shows up
4. Build a short if-then early-warning plan using those signs
</task>

<output_format>
- Mechanism explanation in two short sections (threat response, then emotional regulation), plain but not dumbed down
- One paragraph on why a short fuse specifically, not just fatigue
- A list of two to three early warning signs
- A short if-then plan matched to those signs
- Length: 350 to 450 words
- Tone: clear, respectful of the reader's intelligence, no scaremongering about sleep
</output_format>