Tired but Wired: Why You Are Exhausted but Cannot Sleep

Tired but wired is a body that is short of sleep and a brain that is still on alert, the pattern sleep researchers call hyperarousal. Reviews of people with chronic insomnia find raised arousal in the nervous system, the stress hormones and the brain's electrical activity, day and night, so the exhaustion is real and so is the alertness that overrides it.¹ It is a symptom with everyday causes, not a diagnosis, and "adrenal fatigue" is not one of them; the causes below run in the order worth checking.

What does "tired but wired" mean?

The 2010 review that set out the hyperarousal model of insomnia drew on autonomic, hormonal, EEG and brain-imaging studies and found increased arousal in people with primary insomnia at night and by day. It described insomnia as the end point of a genetic tendency towards arousal, life stressors, and then the habits and worries that keep it going.¹ So "wired" is arousal sitting on top of sleep loss, not surplus energy, which is why lying in longer rarely fixes it.

Is it adrenal fatigue?

No. "Adrenal fatigue" is not recognised by any endocrinology society, and a 2016 systematic review of 58 studies that measured cortisol against fatigue found conflicting results throughout and concluded that there is no substantiation for it as a medical condition.⁵ The term describes a real feeling; the explanation is not a tired gland.

In healthy people most of the day's cortisol is released in the hours around waking, with a sharp rise in the first 30 to 45 minutes after getting up, so a pre-dawn climb is the hormone doing its job.³ Across 20 case-control studies, people with chronic insomnia had moderately higher cortisol than good sleepers (449 patients against 357 controls, standardised mean difference 0.50), a finding that cannot say which came first and says nothing about any one person's night.² And a night of lost sleep did not significantly raise cortisol across 21 crossover studies; the difference reached significance only in subgroups, such as the studies using blood samples.⁴ None of this describes a "cortisol reset". Unexplained weight change, new high blood pressure, easy bruising or dizziness on standing point to the adrenal conditions that do exist: see a GP.

Is it caffeine you had hours ago?

Often, yes. A 2023 meta-analysis of 24 studies found that caffeine cut total sleep by 45 minutes and sleep efficiency by 7%, added 9 minutes to the time taken to fall asleep and 12 minutes of waking in the night, and took 11.4 minutes off deep sleep. To avoid losing total sleep time, the authors calculated that a 107 mg coffee (one 250 mL cup) should be finished at least 8.8 hours before bed.⁶ For an 11pm bedtime that is a last coffee at about 2pm. The NHS says "do not smoke or drink alcohol, tea or coffee at least 6 hours before going to bed"; the 8.8-hour figure is a model estimate, not a trial arm, so the two make a range.¹⁵ Tea, cola and energy drinks count (what to drink before bed, caffeine and sleep); rooibos is caffeine-free (what rooibos is good for).

Is it your evening light and screens?

The room light matters at least as much as the phone. In 55 adults, the dose of evening light that halved melatonin was 24.6 lux, dimmer than most living rooms, and 10, 30 and 50 lux delayed melatonin onset by 22, 77 and 109 minutes.⁷ In 116 volunteers, ordinary room light (under 200 lux) in the eight hours before bed delayed melatonin onset in 99% and shortened the melatonin night by about 90 minutes against dim light.⁸ Main lights down after dinner and one low, warm lamp is the change those numbers point to; the NHS says, "do not use smartphones or screens in the hour before sleep".¹⁴

Is it stress you have carried to bed?

"Sleep reactivity" is the trait that decides how much a stressful day disturbs a person's sleep: reactive sleepers lose sleep sharply under stress, high reactivity predicts future insomnia, shift-work disorder, depression and anxiety, and worry and rumination amplify it.⁹ There is also bedtime procrastination: going to bed later than you meant to, with nothing stopping you, was linked to insufficient sleep in a survey of 177 adults.¹⁰

Could it be a delayed body clock?

If you cannot fall asleep before 1am but sleep soundly when allowed to lie in, the problem may be timing rather than arousal. Delayed sleep-wake phase disorder is the most common body-clock disorder, is often confused with sleep-onset insomnia, usually emerges in the teens, and means sleep that is normal in length and quality but shifted late.¹¹ A two-week diary showing short workday nights and long, good free-day sleep is the clue; it needs a GP conversation about timing, not more sleep hygiene.

What helps a wired evening?

A 2024 network meta-analysis of 241 trials and 31,452 adults with chronic insomnia rated cognitive restructuring (incremental odds of remission 1.68), sleep restriction (1.49) and stimulus control (1.43) as the critical parts of cognitive behavioural therapy for insomnia; sleep hygiene education was not essential (1.01), and relaxation procedures on their own were potentially counterproductive (0.81, a non-significant result).¹² Relaxing harder in bed is the weakest lever; getting up when alert and returning only when sleepy is one of the strongest, and the NHS says the same: "only go to bed when you're sleepy".¹⁵

One addition has a meta-analysis behind it: a warm bath or shower at 40 to 42.5 °C, one to two hours before bed for as little as 10 minutes, shortened the time to fall asleep and improved self-rated sleep quality across 13 studies.¹³ Writing your worries down earlier in the evening keeps the rumination out of the bedroom. Lights down, bath, list, then bed only when sleepy: that is the 90-minute bedtime routine for adults the evidence supports.

The GB register carries no authorised claim for any ingredient about switching off the mind; the wording it does carry for magnesium is that it contributes to normal psychological function and to the reduction of tiredness and fatigue, and the trial figures are in does magnesium help you sleep?. Each ingredient's trial results are in which sleep supplements have evidence behind them, inside the Wellgard sleep guide, and the L-theanine page sets out its trials and its register position. Ashwagandha root extract has sleep trials of its own, is contraindicated in pregnancy, raises thyroid hormone levels, carries published liver-injury reports and is under a UK safety assessment whose Committee on Toxicity statement is pending: read the Wellgard ashwagandha guide, who should not take ashwagandha and is ashwagandha safe to take daily first.

When is tired but wired something to get checked?

The NHS tiredness page says to see a GP if "you've been feeling tired for a few weeks and you're not sure why" or "you feel tired and have other symptoms, such as weight loss or mood changes, or you've been told you're making gasping, snorting or choking noises when you're asleep"; the GP may arrange "blood tests to check for anaemia, diabetes or hyperthyroidism".¹⁴ Overactive thyroid mimics tired but wired closely: "Tired all the time, finding it hard to stay still, feeling nervous, anxious and irritable, muscle weakness".¹⁴ For the sleep itself, see a GP if changing your habits has not helped, if it has lasted months, or if it is making it hard to cope; you may be offered cognitive behavioural therapy, face to face or online.¹⁵ NHS 111 "can help if you think you need medical help right now", including when your GP is closed;¹⁶ 999 "is for life-threatening emergencies like serious road traffic accidents, strokes and heart attacks",¹⁷ and if you feel that you may be about to harm yourself, call 999 or go straight to A&E.¹⁸ The full list is in when to see a GP about sleep.

Frequently asked questions

Why do I get a second wind at night?

The body clock's alerting signal is still running in the hours before your usual bedtime and falls away as melatonin rises; ordinary room light delays that rise by an hour or more, stretching the "second wind" past midnight.^{7, 8} Dim lights after dinner and a fixed wake time pull it back.

Is tired but wired the same as insomnia?

No, it is a symptom. The NHS defines insomnia as regularly finding it hard to go to sleep, waking in the night or early (why do I wake up at 3am), or still feeling tired on waking; short-term is under 3 months, long-term 3 months or more.¹⁵

Can ADHD, thyroid problems or bipolar disorder make you tired but wired?

They can present this way: the NHS lists overactive thyroid and bipolar disorder among conditions that can cause insomnia.¹⁵ None is diagnosed from a sleep pattern alone; if the alertness comes with the thyroid signs above, mood that swings high as well as low, or lifelong difficulty settling and focusing, take it to a GP.

Sources

1. Riemann D et al. The hyperarousal model of insomnia: a review of the concept and its evidence. Sleep Medicine Reviews 2010. PubMed 19481481
2. Dressle RJ et al. HPA axis activity in patients with chronic insomnia: a systematic review and meta-analysis of case-control studies. Sleep Medicine Reviews 2022. PubMed 35091194
3. Stalder T et al. The cortisol awakening response: regulation and functional significance. Endocrine Reviews 2025. PubMed 39177247
4. Chen Y et al. The effect of acute sleep deprivation on cortisol level: a systematic review and meta-analysis. Endocrine Journal 2024. PubMed 38777757
5. Cadegiani FA, Kater CE. Adrenal fatigue does not exist: a systematic review. BMC Endocrine Disorders 2016. PubMed 27557747
6. Gardiner C et al. The effect of caffeine on subsequent sleep: a systematic review and meta-analysis. Sleep Medicine Reviews 2023. PubMed 36870101
7. Phillips AJK et al. High sensitivity and interindividual variability in the response of the human circadian system to evening light. Proceedings of the National Academy of Sciences 2019. PubMed 31138694
8. Gooley JJ et al. Exposure to room light before bedtime suppresses melatonin onset and shortens melatonin duration in humans. Journal of Clinical Endocrinology and Metabolism 2011. PubMed 21193540
9. Kalmbach DA et al. The impact of stress on sleep: pathogenic sleep reactivity as a vulnerability to insomnia and circadian disorders. Journal of Sleep Research 2018. PubMed 29797753
10. Kroese FM et al. Bedtime procrastination: introducing a new area of procrastination. Frontiers in Psychology 2014. PubMed 24994989
11. Nesbitt AD. Delayed sleep-wake phase disorder. Journal of Thoracic Disease 2018. PubMed 29445534
12. Furukawa Y et al. Components and delivery formats of cognitive behavioral therapy for chronic insomnia in adults: a systematic review and component network meta-analysis. JAMA Psychiatry 2024. PubMed 38231522
13. Haghayegh S et al. Before-bedtime passive body heating by warm shower or bath to improve sleep: a systematic review and meta-analysis. Sleep Medicine Reviews 2019. PubMed 31102877
14. NHS. Tiredness and fatigue. Reviewed 2 June 2023. nhs.uk
15. NHS. Insomnia. Reviewed 19 March 2024. nhs.uk
16. NHS. When to use NHS 111 online or call 111. nhs.uk
17. NHS. When to call 999. nhs.uk
18. NHS. Help for suicidal thoughts. nhs.uk