Waking Up at 4am: Cortisol, Blood Sugar, Stress — Causes and Solutions
By the Mush n Go editorial team - 10 November 2026
By the Mush n Go editorial teamPublished 10 November 202614 min read
Sleep and cortisol
Waking up at 4am is often explained by the end of the night itself: sleep becomes lighter, melatonin falls and cortisol begins its morning rise. Stress, alcohol, late caffeine, sleep apnoea or age then make waking more likely. Here is how to spot your cause, what to do in the moment, and when to see a doctor.
The complete guide: how to lower cortisol naturally →
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By 4am, your night has already changed its nature.
Waking up at 4am, wide awake, unable to get back to sleep: it is one of the most common sleep complaints. It is not a quirk of the clock. If you went to bed around 11pm, you have slept for five hours, that is three to four sleep cycles, and your night no longer has the same structure at all as it did at the start.
The first part of the night is where deep sleep is concentrated, the hardest stage to interrupt. The second part is made up of light sleep and REM sleep, during which you wake far more easily. Here, simplified, is what happens hour by hour for someone who goes to bed at 11pm.
11pm – 1am
Falling asleep, then deep sleep. The sleep pressure built up during the day is at its highest. You rarely wake.
1am – 3am
Melatonin is at its highest level. Cortisol is at its lowest. Deep sleep becomes scarcer from one cycle to the next.
3am – 5am
Lighter sleep, longer REM sleep. Sleep pressure has largely been discharged, and cortisol starts to rise again. This is the waking zone.
On waking
Cortisol peaks in the half-hour after you get up: this is the cortisol awakening response, normal and useful.
In other words, around 4am everything is in place for a small stimulus to wake you: a noise, needing to pee, a hot flush, a thought. The real question is not “why do I wake up?”, because brief awakenings are normal, but “why can't I get back to sleep?”.
Cortisol and sleep
Cortisol rises before dawn, and stress brings it forward.
Cortisol follows a 24-hour rhythm. It is at its lowest around the start of the night, rises gradually during the second half, then peaks in the half-hour after waking. This morning peak is normal: it helps you get going. When people search for “what time does cortisol peak”, this is the peak they mean.
The link between cortisol and sleep runs both ways. Major stress, a period of overload or rumination keep the body on alert. The late-night rise then meets more reactive ground, and a brief awakening turns into being fully awake, with a mind that starts racing straight away about the next day's worries. Conversely, repeated short nights disrupt the cortisol rhythm.
What is established
The cortisol rhythm, its peak on waking, and the fact that stress and hyperarousal encourage early-morning insomnia.
What is oversimplified
The idea of a “4am cortisol spike” that would wake everyone up. Cortisol rises gradually; it does not set off an alarm at a fixed time.
What is false
That waking at 4am necessarily means “cortisol is too high”. A blood test is only justified on medical advice, alongside other signs.
What matters
What you do with your day and evening: that is where the 4am state of alert is set up.
If you are wondering whether your cortisol is to blame, our article on testing your cortisol explains what the tests really measure, and our guide on how to lower cortisol ranks the levers by strength of evidence.
What the studies say
The end of the night: four studies worth knowing.
Here are four pieces of research that explain why the end of the night is fragile, and what makes it even more so. Full references are at the bottom of the page.
Pruessner et al., 1997 · Germany
By measuring cortisol in saliva just after waking and then every 15 minutes, the team showed that free cortisol rises by around 50% in the half-hour after waking, reproducibly from one day to the next. This is the cortisol awakening response.
Ohayon et al., 2004 · United States
This meta-analysis pooled the sleep recordings of more than 3,500 healthy people, from childhood to old age. With age, deep sleep decreases and awakenings during the night increase. Waking more often at 60 than at 30 is part of normal ageing.
Ebrahim et al., 2013 · United Kingdom, Canada
This review of alcohol and sleep concludes that alcohol speeds up falling asleep and deepens the first part of the night, but disrupts the second half: more restless sleep, more frequent awakenings. An evening drink can therefore explain waking at around 3 or 4am.
Drake et al., 2013 · United States
A high dose of caffeine, taken even six hours before bedtime, cut the night short by more than an hour in adults who normally slept well. Participants did not always notice: a late-afternoon coffee can quietly weaken the end of the night.
These studies point the same way: the end of the night is naturally lighter, and several very common habits, alcohol and caffeine first among them, make it more fragile still.
Other causes
Insomnia at 4am: the causes to go through.
Stress is not the only explanation. Before concluding it is “a cortisol problem”, go through the most common causes. Several can add up.
| Possible cause | Telltale signs | What you can do |
|---|---|---|
| Stress, rumination | Mind racing as soon as you wake, a busy period | A wind-down routine in the evening, a technique for the night (see below) |
| Alcohol in the evening | Waking mainly on nights you have been drinking, sweating | No alcohol in the 3 to 4 hours before bedtime |
| Late caffeine | Coffee, tea, cola or chocolate after 2pm | Have your last coffee earlier, switch to decaf or chicory |
| Sleep apnoea | Snoring, pauses in breathing, waking with a dry mouth, daytime sleepiness | See a doctor: it can be diagnosed and treated |
| Needing to pee | Waking to go to the toilet, several times a night | Cut down on drinks in the evening; talk to your doctor if it happens often |
| Night-time blood sugar | Treated diabetes, sweating, hunger, palpitations at night | Talk to your doctor, who can adjust your treatment |
| Menopause | Hot flushes, night sweats | A cool bedroom, talk to your GP or gynaecologist |
| Age | Lighter, shorter sleep than before, with no daytime tiredness | Nothing abnormal if you feel well during the day |
| Low mood | Early waking with dark thoughts, loss of interest, lasting sadness | See your doctor: this is a sign to take seriously |
This table helps point you in the right direction; it does not replace medical advice. Causes often stack up: a glass of wine, a coffee at 4pm and a stressful week are enough to weaken the end of the night.
Night-time blood sugar comes up a lot on social media. In people with diabetes treated with insulin or certain medicines, nocturnal hypoglycaemia can indeed wake you up. In everyone else the evidence is weak: a balanced dinner, neither too late nor too light, is still a good habit, but on its own it will not solve a waking problem. For the menopause, our article on sleep solutions during the menopause goes further.
When to see a doctor
Some awakenings deserve an appointment.
Insomnia is called chronic when sleep difficulties occur at least three nights a week, for at least three months, and affect your day: tiredness, irritability, difficulty concentrating. At that stage it is better to talk to a doctor than to keep trying things on your own.
See your doctor without delay if:
- You snore loudly, the people around you notice pauses in your breathing, or you feel sleepy during the day, especially at the wheel.
- Your early waking comes with sadness, loss of interest or dark thoughts. If you are having suicidal thoughts, call Samaritans on 116 123, free, 24 hours a day.
- You wake up with palpitations, heavy sweating, breathlessness or pain.
- You have diabetes and suspect night-time hypos.
- Your insomnia has lasted more than three months, or it started with a new medicine.
The good news is that chronic insomnia responds well to treatment. Cognitive behavioural therapy for insomnia, or CBT-I, is the first-line treatment recommended by European sleep societies, ahead of medication. It relies on simple techniques: regular hours, restricting time spent in bed, and working on the thoughts that keep you awake.
What to do at 4am
Awake at 4am: three steps, and don't check the time.
What you do in the minutes after waking often decides what happens next. The classic trap: checking the time, working out how long is left, worrying about the next day, and ending up wide awake. Here is a method inspired by CBT-I.
Don't check the time
Turn the clock away, keep your phone out of reach. Knowing it is 4:12am does not help you get back to sleep, and it sets off the anxious countdown of the hours left.
Slow your breathing
Breathe out for longer than you breathe in, for example 4 seconds in and 6 out, for a few minutes. Let thoughts pass without following them.
Get up if sleep won't come
If you are still awake after twenty minutes or so, estimated without a watch, get up. Dim light, a calm activity, a paper book. Go back to bed when sleepiness returns.
- No screens: the light and the content wake you up even more.
- No coffee or sugary snacks “to keep going”: you would only shift the problem to the following night.
- Keep a notebook by the bed: write down the thought that keeps circling, with a promise to deal with it tomorrow.
- The next day, get up at your usual time, even after a bad night: that is what resets the clock.
What helps during the day
Good nights are prepared from the morning.
Most of the levers that act on early-morning waking lie outside the bedroom. They are simple habits, but they count for more than any supplement.
- Morning light. Twenty minutes or so outdoors in the first hour after getting up helps set your body clock, and therefore the time your night ends.
- A fixed wake-up time. Even at weekends, give or take an hour. It is the most powerful cue for your rhythm.
- Caffeine before 2pm. Our article on the coffee cut-off time explains why the afternoon cup weighs on your night.
- A dinner that is neither too late nor too heavy. Two to three hours before bedtime, without too much alcohol.
- Physical activity. Regular, ideally during the day rather than late in the evening.
- An evening that slows down. Dimmed lights, screens put away, a moment to “empty” your head on paper.
For a complete list, our guide sleeping well: 15 evening habits goes through each habit. If you drink several coffees a day, switching to a less caffeinated coffee in the afternoon is often the simplest change: a cup of Brainstoorm contains 20 mg of caffeine, compared with around 80 mg for an espresso.
Supplements
Melatonin, magnesium, herbs: what has evidence.
Supplements are often the first reflex, yet they come after habits. Here, honestly, is what we know about each one for early-morning waking, which is not the same thing as difficulty falling asleep.
| Supplement | What the data say | For waking at 4am |
|---|---|---|
| Melatonin | Contributes to the reduction of time taken to fall asleep (authorised claim). In meta-analysis, a modest gain of a few minutes | Acts mainly on falling asleep, little on early waking |
| Magnesium | An Iranian trial in 46 older people with insomnia observed an improvement in several measures, including early waking | An interesting lead, but a single small trial, in older adults |
| Valerian | 2006 meta-analysis: possible improvement in perceived sleep quality, with a risk of publication bias | Weak data, long traditional use |
| Reishi | Traditional use, animal data, no conclusive human trial on sleep | No evidence in humans |
| Sleeping pills | Effective in the short term, risks of dependence and next-day drowsiness | On prescription only, for a short period |
Melatonin supplements are not recommended by the French health agency ANSES for pregnant or breastfeeding women, children and teenagers, and require medical advice in cases of epilepsy, asthma or mood disorders. Avoid it before any activity that requires alertness.
To compare the two most common evening options, our article valerian or melatonin sets out the facts. And for magnesium, our guide to magnesium bisglycinate explains why this form is so often chosen.
An evening routine
Where Sleep+ fits into your evening.
Sleep+ combines reishi, valerian, magnesium bisglycinate, acacia fibre and melatonin. Melatonin contributes to the reduction of time taken to fall asleep: this is its only authorised claim, and it concerns falling asleep, not waking at the end of the night. If your main problem is waking at 4am, Sleep+ can be part of a routine, but it does not replace one.
In the morning
A fixed wake-up time, daylight, your coffee. Those following a daytime anti-stress routine take Anti-Stress at this point, with a glass of water.
Around 2pm
Last regular coffee. After that, decaf, chicory or a low-caffeine drink.
At dinner
A complete meal two to three hours before bedtime, with little or no alcohol.
30 minutes before bedtime
1 to 2 capsules of Sleep+, low light, screens put away, a few lines in a notebook.
If you wake up
No clock, no screen, slow breathing, and get up if sleep doesn't come back. No extra capsule in the middle of the night.
To cover morning, daytime and evening in a single order, our Perimenopause Pack brings together Brainstoorm, Anti-Stress and Sleep+.
Precautions with Sleep+:
- Not recommended for pregnant and breastfeeding women, or for children and teenagers under 12.
- Not recommended for people with inflammatory or autoimmune diseases.
- Medical advice required in cases of epilepsy, asthma, or mood, behavioural or personality disorders, because of the melatonin.
- Do not take Sleep+ before driving or operating machinery, and do not exceed the recommended dose.
- The reishi it contains may interact with certain medicines, including anticoagulants: talk to your doctor if you are on treatment.
The Relaxation Pack brings together Anti-Stress and Sleep+ for those who want a routine across the whole day. To find out more about the evening ingredients, see our page on valerian.
The Perimenopause Pack
Brainstoorm in the morning, Anti-Stress during the day, Sleep+ in the evening: all three products together in a 30-day ritual, cheaper than buying them separately, as a one-off purchase or a subscription.
Discover the Perimenopause Pack →Your questions
Waking up at 4am: your questions.
Why do I wake up at 4am?
Because at the end of the night sleep is lighter, sleep pressure has been discharged and cortisol is starting to rise. A small trigger is then enough to wake you: stress, alcohol, late caffeine, needing to pee, a hot flush or sleep apnoea. Age also makes these awakenings more frequent.
Is it cortisol that wakes me up at night?
It contributes, without being an alarm set for a fixed time. Cortisol rises gradually in the second half of the night and peaks just after waking. Stress makes the body more reactive to this rise, which turns a brief awakening into being fully awake.
What time is cortisol highest?
In the half-hour after waking in the morning, when it rises by around 50%. It is at its lowest at the start of the night, rises during the second half, then falls gradually over the day.
What should you do when you wake at 4am and can't get back to sleep?
Don't check the time, slow your breathing and let thoughts pass. If sleep hasn't returned after twenty minutes or so, get up for a calm activity in dim light, without a screen, then go back to bed when you feel sleepy.
Can stress cause early-morning insomnia?
Yes. Stress keeps you in a state of alert that makes waking at the end of the night more likely and longer. This is often the case during periods of overload or worry. An evening wind-down routine and regular hours help, and CBT-I is recommended if it persists.
Does alcohol make you wake up at night?
Yes. Alcohol helps you fall asleep but disrupts the second half of the night, with more restless sleep and more frequent awakenings. Waking around 3 or 4am after an evening of drinking is a typical example.
Does melatonin stop you waking at 4am?
Not really. Melatonin contributes to the reduction of time taken to fall asleep, but data on waking at the end of the night are limited. It is not recommended for pregnant or breastfeeding women or for children, and requires medical advice in cases of epilepsy, asthma or mood disorders.
When should you see a doctor about waking at night?
If the awakenings happen at least three nights a week for three months, if you are tired during the day, if you snore loudly with pauses in breathing, or if the awakenings come with sadness or dark thoughts. If you are having suicidal thoughts, call Samaritans on 116 123.
Is waking up at night normal with age?
Yes, partly. With age, deep sleep decreases and night-time awakenings become more frequent. If you feel well during the day, it is not a problem. If you are tired, talk to your doctor.
Sources
- Pruessner J. C. et al. (1997). Free cortisol levels after awakening: a reliable biological marker for the assessment of adrenocortical activity. Life Sciences, 61(26), 2539-2549.
- Ohayon M. M., Carskadon M. A., Guilleminault C., Vitiello M. V. (2004). Meta-analysis of quantitative sleep parameters from childhood to old age in healthy individuals. Sleep, 27(7), 1255-1273.
- Ebrahim I. O., Shapiro C. M., Williams A. J., Fenwick P. B. (2013). Alcohol and sleep I: effects on normal sleep. Alcoholism: Clinical and Experimental Research, 37(4), 539-549.
- Drake C., Roehrs T., Shambroom J., Roth T. (2013). Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. Journal of Clinical Sleep Medicine, 9(11).
- Gardiner C. et al. (2023). The effect of caffeine on subsequent sleep: a systematic review and meta-analysis. Sleep Medicine Reviews, 69.
- Claustrat B., Leston J. (2015). Melatonin: physiological effects in humans. Neurochirurgie, 61(2-3), 77-84.
- Riemann D. et al. (2017). European guideline for the diagnosis and treatment of insomnia. Journal of Sleep Research, 26(6), 675-700.
- Ferracioli-Oda E., Qawasmi A., Bloch M. H. (2013). Meta-analysis: melatonin for the treatment of primary sleep disorders. PLoS One, 8(5), e63773.
- Abbasi B. et al. (2012). The effect of magnesium supplementation on primary insomnia in elderly: a double-blind placebo-controlled clinical trial. Journal of Research in Medical Sciences, 17(12), 1161-1169.
- Bent S., Padula A., Moore D., Patterson M., Mehling W. (2006). Valerian for sleep: a systematic review and meta-analysis. The American Journal of Medicine, 119(12), 1005-1012.
- ANSES (2018). Opinion on the risks associated with the consumption of food supplements containing melatonin (in French). Request No. 2016-SA-0209.
Keep reading
Further reading.
Waking at the end of the night touches on both stress and sleep. Explore our other guides, or our Sleep+ formula.
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