Running on borrowed energy
Why do I get a burst of energy under pressure, then crash?
The stress high is real and it gets things done. The crash that often follows isn't a separate problem: it may be the bill.
Short answer
Many people get a surge of energy and focus under deadline pressure, then a slump a day later. Lab studies show emotional states change heart rate and other bodily activity quickly, which can feel like energy. Calling the surge a loan and the crash its repayment is a Calmistry metaphor, not a measured mechanism. Capping how long you sprint, protecting recovery and tracking the crash, not just the output, are reasonable first steps.
Part of a bigger question: Why do I crash once a stressful week is over?
You hit a deadline and something kicks in: a clean surge of energy, focus narrowing, output pouring out. For a few hours you're unstoppable, and it feels good. The work gets done. The high is real, not imagined, and a part of you quietly relies on it.
Then, a day later, you're flattened. Short-fused, foggy, the morning impossibly heavy. And almost nobody connects the crash back to the high that came before it.
The high is real, and it may be a loan
Two things are true at once, which is what makes this one slippery. Pressure tends to mobilise the body fast, with arousal and focus rising, so the surge is real and it does get things done. Moderate evidence And it may be borrowed rather than free: drawn against reserves rather than generated fresh. That second part is a working metaphor, not something anyone has measured directly. Speculative
Read that way, the crash may not be a separate misfortune that happens to follow good days, but the repayment. That is the metaphor talking; the research does not yet show the surge and the slump share one account. A plainer contributor is sleep: studies of working adults found stressful periods and bedtime work worry went with poorer sleep, Moderate evidence and a short night alone can produce a heavy morning. Other explanations compete too: skipped meals, caffeine wearing off, or simply the ordinary dip once a deadline is gone.
Why chasing the high deepens the hole
Once you know the high feels good and works, the temptation is to summon it again: more caffeine, more pressure, more sprinting. Our model predicts that the crashes get deeper and closer together when the borrowing never gets paid back. Nobody has measured that properly yet, which is a good reason to measure it on yourself.
Praise for heroics makes it worse in a quieter way. Get celebrated for the output and you're rewarded for borrowing, right up until the account won't cover the next withdrawal.
What settles it
Two moves, and they work best together. Cap the sprint: put a real ceiling on how long you'll run hot, before you're empty rather than after. And repair recovery deliberately: the sleep, the actual break, the meal, the evening where work stays switched off. Research on recovery finds that people who detach from work tend to report less exhaustion. Moderate evidence
The shift is to measure the crash, not just the output. Output is what gets noticed; the crash is what tells you what the output actually cost.
What to watch
Try comparing two sprints: one where you stopped at a set time and slept normally, one where you ran until empty. Note how long each spike lasted, when the slump landed and how ready you felt the next day. If the capped sprint costs less the next day, the loan picture fits you. If both crash the same, look at sleep, food or illness first. Small sprints that add up are close to what Calmistry calls fatigue, and The long carry quiz looks at what long loads tend to do over time.
Other causes and when to get checked are listed below the article.
Pay the loan down
The spike will stay tempting because it gets results. But it may be borrowed, and the crash is the interest. Cap the sprint, repair the recovery, and measure what the high costs, not just what it produces.
The spike isn't free energy. It's a loan. And the crash that shows up later, on schedule, is the loan collecting.
Before you read anything into it
A body signal can suggest that something merits attention. It cannot tell you which mechanism caused it or what material you are.
Other things that can cause this
- Sleep debt or an irregular sleep schedule
- Blood sugar swings from skipped or heavy meals, or caffeine wearing off
- Illness, anaemia or thyroid problems
- Low mood, which can look like a crash that does not lift
When to get it checked
See a doctor if exhaustion is new, lasts more than a couple of weeks, does not lift with rest, or comes with weight change, breathlessness, fever or low mood most days.
Keep investigating
Where this fits: the mechanism behind it, a material that responds differently, and the Field Guide it belongs to.
What the evidence can't tell you Lab studies of emotion and heart rate cannot tell you whether your slump repays the surge; the loan picture is a Calmistry metaphor.
Take it further
Measures this touches
Response patterns that meet it
Claims and evidence
Each claim in this article, as an observed pattern, a plausible mechanism and the strength of the evidence.
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Observed in studies Moderate
- What studies found
- A review of experiments in healthy people found that emotional states come with distinct patterns of bodily activation, such as changes in heart rate.
- One explanation
- Stress tends to mobilise the body quickly (heart rate, alertness), which can feel like a burst of energy in the moment.
- What it does not show
- Short lab inductions of emotion; they describe the activation, not a later crash, and not how long anyone can sustain it.
- Evidence
- Several studies or a meta-analysis support it, with mixed sizes or open questions.
Kreibig 2010Narrative review
- Who
- 134 experimental publications on healthy people
- Conditions
- Different emotions
- Method
- Review of automatic bodily responses such as heart rate
- Observed
- Different emotions, especially their subtypes, showed fairly distinct patterns of automatic bodily responses.
- Design
- Narrative review
Autonomic nervous system activity in emotion: A review. Biological Psychology. doi:10.1016/j.biopsycho.2010.03.010
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Observed in studies Moderate
- What studies found
- People who detach from work and get real recovery time tend to report less exhaustion.
- One explanation
- Recovery periods appear to let strain come back down; links with physiological markers are weaker than links with how people feel.
- What it does not show
- Mostly employee self-report surveys; they link recovery with less exhaustion without showing that a crash is repayment for a surge.
- Evidence
- Several studies or a meta-analysis support it, with mixed sizes or open questions.
Sonnentag & Fritz 2015Narrative review
- Conditions
- Mentally switching off from work during free time
- Method
- Review of cross-sectional, longitudinal and daily diary studies
- Observed
- Heavy workload went with less switching off after work, and less switching off went with more strain and poorer well-being.
- Design
- Narrative review
Recovery from job stress: the stressor-detachment model. Journal of Organizational Behavior. doi:10.1002/job.1924
Wendsche & Lohmann-Haislah 2017Meta-analysis
- Who
- Employee samples totalling 38,124 people
- Conditions
- Mentally detaching from work during non-work time
- Method
- Pooled correlations with health, well-being and performance
- Observed
- Detaching from work was linked with less exhaustion, better sleep and well-being, while higher job demands went with less detachment.
- Design
- Meta-analysis
A meta-analysis on antecedents and outcomes of detachment from work. Frontiers in Psychology. doi:10.3389/fpsyg.2016.02072
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Observed in studies Moderate
- What studies found
- In studies of working adults, stressful periods and bedtime work worry went with poorer sleep.
- One explanation
- Arousal and work worry at bedtime may make sleep lighter or shorter, so readiness the next day drops.
- What it does not show
- Largely observational; poorer sleep is one plausible route to a next-day slump, among several.
- Evidence
- Several studies or a meta-analysis support it, with mixed sizes or open questions.
Åkerstedt 2006Narrative review
- Conditions
- Psychological stress and sleep
- Method
- Review of survey and sleep recording studies
- Observed
- Stress went with shorter, more broken sleep, and dreading the next day's demands seemed especially important.
- Design
- Narrative review
Psychosocial stress and impaired sleep. Scandinavian Journal of Work, Environment & Health. doi:10.5271/sjweh.1054
Sources
- Kreibig 2010. Autonomic nervous system activity in emotion: A review. Biological Psychology. doi:10.1016/j.biopsycho.2010.03.010
- Sonnentag & Fritz 2015. Recovery from job stress: the stressor-detachment model. Journal of Organizational Behavior. doi:10.1002/job.1924
- Wendsche & Lohmann-Haislah 2017. A meta-analysis on antecedents and outcomes of detachment from work. Frontiers in Psychology. doi:10.3389/fpsyg.2016.02072
- Åkerstedt 2006. Psychosocial stress and impaired sleep. Scandinavian Journal of Work, Environment & Health. doi:10.5271/sjweh.1054
Situation quiz
The long carry
You know the surge before the deadline and the slump after it. Does the same rhythm show up at work, at home and around big events?
About 12 minutes. It describes a tendency across situations, not a fixed identity, and it can change.