Why can't I switch off?
You lie in bed at 11 p.m. Your body is tired, but your mind is still in the last meeting. At 3 a.m. you wake up and the to-do list starts running. On holiday it takes you four or five days to really relax. By then, it is almost time to fly home, and the inbox is waiting.
If this sounds familiar, here is the first thing to know: it is not you. Your nervous system is doing exactly what it was built to do.
A system built not to switch off
Your body runs two stress systems. The nervous system reacts in seconds: adrenaline, a faster heart, sharper focus. This is sympathetic mode, often called fight or flight. The hormonal system, the HPA axis (hypothalamus, pituitary and adrenal glands), reacts over minutes to hours and releases cortisol.
Both follow one rule: as long as the brain perceives a threat, do not shut down. A deadline, a difficult client or an open conflict counts as a threat. So does a thought about them at 11 p.m.
A meta-analysis of 60 studies in Psychological Bulletin shows how strong this effect is. When people keep thinking about past or future problems, their heart rate and cortisol go up, and their heart rate variability (HRV), a marker of recovery, goes down. The thoughts keep the stress response running long after the actual stressor is gone.
When the stress response gets stuck
Bruce McEwen described in the New England Journal of Medicine how the stress response causes wear and tear when it is used too often or does not switch off. One of his patterns is the prolonged response: the system activates normally but fails to shut down after the stress is over.
This is what "I can't switch off" looks like in the body. Two signals stand out.
The nervous system stays in sympathetic mode. Heart rate stays up in the evening, HRV stays low, and the night brings little recovery.
Cortisol stays high in the evening. Normally it falls to its lowest point at night. In a sleep lab study, people with chronic insomnia released more cortisol over 24 hours, with the biggest difference in the evening and the first half of the night. The researchers concluded that the goal should be to lower overall arousal, not just to fix the night.
With high evening cortisol and a nervous system on alert, your brain stays switched on too. The spiral of thoughts is not a character flaw. It is a body that has not received the signal that the day is over.
The honeymoon phase, and what comes after
At first, this state can feel productive. Cortisol mobilizes energy, and you get a lot done. Many people in intense jobs know this phase well.
It does not last. A meta-analysis in Psychological Bulletin found that cortisol is elevated when chronic stress begins and drops as time passes.
Martin Picard, a stress researcher at Columbia University, explains why in an energy model of allostatic load, written with Prof. Robert-Paul Juster. Your body has a limited energy budget. Staying on alert costs energy. When that cost stays high, it competes with what they call "growth, maintenance, and repair." The body postpones repair to pay for alertness.
In the short term, that trade is fine. Over months and years, it adds up. Cortisol and cortisone are catabolic: they break down reserves for energy. Hormones like DHEA and testosterone are anabolic: they build and repair. In a Swedish study, people who reported stress at work had 23% lower DHEA-S, the storage form of DHEA. When the balance tips toward breakdown, the body slowly loses ground.
The next stage is often fatigue. Researchers have proposed that low cortisol can follow a long period of overactivation, together with higher stress sensitivity, pain and fatigue. That stage takes much longer to reverse.
This is why the switch-off phase is the best moment to act. The system is still strong. It needs to learn to come down again.
Holidays are not enough
A meta-analysis of vacation studies found that holidays improve health and wellbeing, but the effect fades soon after people return to work. What protects you is daily recovery. In a meta-analysis of 38,124 employees, people who detached better from work after hours reported less exhaustion, better sleep and less fatigue.
Start with rebalancing, not more willpower
If the stress response is stuck, telling yourself to relax will not help much. The first step is neurobiological rebalancing: bringing the hormonal system and the nervous system back into rhythm. That starts with measurement.
Saliva cortisol profile: 6 samples over two days show whether your cortisol falls in the evening or stays high.
Heart rate monitoring: one week of ECG data shows when your nervous system is in sympathetic mode, when you recover and how much recovery you get at night.
Hair hormones: 3 months of cortisol and cortisone next to DHEA, testosterone and progesterone show your catabolic-to-anabolic balance.
From there, interventions target the exact moments when your stress builds up. A few examples:
Micro-recovery at your peak stress hours. If your data shows stress building between 2 and 6 p.m., a 1 to 2 minute breathing break goes there. Slow breathing raises HRV during and after practice, according to a meta-analysis of 223 studies.
Movement at the right time. A short walk after your last meeting helps your body close the day. If your evening cortisol is high, hard training moves earlier.
A clear evening transition. A hard stop for work after dinner, a short brain dump of open loops and dimmer light.
Targeted nutraceuticals at specific times. Ashwagandha in the evening can support sleep: a meta-analysis of 5 trials found a small but significant effect, stronger at 600 mg a day or more over at least 8 weeks. Rhodiola rosea, usually taken in the morning, showed an anti-fatigue effect in a trial with people with stress-related fatigue. We use them only when your markers point to them, and in agreement with your doctor.
Follow-up tests then show whether your evening cortisol falls and your night-time HRV rises. That is how you know the rebalancing works.
Not being able to switch off is not a lack of discipline. It is a stress response that has not switched back to recovery. At this stage, it is still highly trainable.
Try the Sapiens diagnostics. Order the saliva cortisol test and see whether your cortisol really comes down in the evening. Individual tests start at 159 EUR. Order your cortisol test
Not sure where to start? Take the allostatic load self-assessment or book a discovery call.
References
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2. McEwen BS. Protective and damaging effects of stress mediators. N Engl J Med. 1998;338(3):171-179. doi.org/10.1056/NEJM199801153380307
3. Vgontzas AN, et al. Chronic insomnia is associated with nyctohemeral activation of the hypothalamic-pituitary-adrenal axis: clinical implications. J Clin Endocrinol Metab. 2001;86(8):3787-3794. doi.org/10.1210/jcem.86.8.7778
4. Miller GE, Chen E, Zhou ES. If it goes up, must it come down? Chronic stress and the hypothalamic-pituitary-adrenocortical axis in humans. Psychol Bull. 2007;133(1):25-45. doi.org/10.1037/0033-2909.133.1.25
5. Bobba-Alves N, Juster RP, Picard M. The energetic cost of allostasis and allostatic load. Psychoneuroendocrinology. 2022;146:105951. doi.org/10.1016/j.psyneuen.2022.105951
6. Lennartsson AK, et al. Perceived stress at work is associated with lower levels of DHEA-S. PLoS One. 2013;8(8):e72460. doi.org/10.1371/journal.pone.0072460
7. Fries E, Hesse J, Hellhammer J, Hellhammer DH. A new view on hypocortisolism. Psychoneuroendocrinology. 2005;30(10):1010-1016. doi.org/10.1016/j.psyneuen.2005.04.006
8. de Bloom J, et al. Do we recover from vacation? Meta-analysis of vacation effects on health and well-being. J Occup Health. 2009;51(1):13-25. doi.org/10.1539/joh.k8004
9. Wendsche J, Lohmann-Haislah A. A meta-analysis on antecedents and outcomes of detachment from work. Front Psychol. 2017;7:2072. doi.org/10.3389/fpsyg.2016.02072
10. Laborde S, et al. Effects of voluntary slow breathing on heart rate and heart rate variability: a systematic review and a meta-analysis. Neurosci Biobehav Rev. 2022;138:104711. doi.org/10.1016/j.neubiorev.2022.104711
11. Cheah KL, et al. Effect of Ashwagandha (Withania somnifera) extract on sleep: a systematic review and meta-analysis. PLoS One. 2021;16(9):e0257843. doi.org/10.1371/journal.pone.0257843
12. Olsson EM, von Schéele B, Panossian AG. A randomised, double-blind, placebo-controlled, parallel-group study of the standardised extract SHR-5 of the roots of Rhodiola rosea in the treatment of subjects with stress-related fatigue. Planta Med. 2009;75(2):105-112. doi.org/10.1055/s-0028-1088346
