How late is too late for caffeine?
Keep caffeine at least six hours from bed, and earlier if you can; it lasts far longer than you'd think.
Food, drink & sleep
The afternoon coffee and the evening glass both reach the night, and both reach it later than it feels. This hub is about timing more than about giving things up.
How late is too late for caffeine? has the half-lives, the trial everyone quotes and the review that followed it. It also explains why the NHS figure of six hours is a floor, not a target. More articles are coming on alcohol, late meals and what to drink in the evening.
The timings are the useful part. An instant coffee at 2pm, with a four-hour half-life, still has an eighth of its caffeine in you at 2am. For about half of us the half-life is longer than that. The articles do the sums so you don't have to.
What you won't find here is a list of foods or drinks that help you sleep. The evidence for timing is good; the evidence for most of the rest is thin, and we'd rather say so. Where something has been tested, we'll name the study and its size, and where it hasn't, we'll say that too.
Start here
How late is too late for caffeine?Caffeine
Questions
How late is too late for caffeine?
Six hours before bed at the latest, and earlier if you can; the Royal College of Psychiatrists simply says stop by 2pm. In the trial that tested it, a large dose six hours before bed cost an hour of sleep, and nobody noticed.
Does alcohol help you sleep?
It helps you drop off and then breaks up the second half of the night. The NHS puts it at least six hours before bed, alongside tea and coffee.
Your questions, answered simply and clearly.
Why not just take a magnesium tablet?
Because a tablet is one ingredient and Serune is eight. Each sachet contains 150mg of elemental magnesium as fully reacted, chelated magnesium bisglycinate, whereas many high-street tablets use magnesium oxide. Alongside it are Safr'Inside™ saffron, glycine, L-theanine, lemon balm, chamomile, vitamin B6 and zinc, each at the dose listed on the pack. And it is designed as a warm drink you make each evening, not a tablet you take and forget.
How is it different from chamomile tea?
Same evening warm beverage, but with very different contents. How much a tea bag gives you depends on the flowers, the water and how long you leave it. Serune contains 400mg of chamomile extract in every sachet, standardised to 3% total apigenins, alongside seven other actives at named doses.
How long before I know if it is for me?
Every sachet carries the full dose from the first night. What takes time is the habit. That is why we suggest three packs before you decide: long enough for the ritual to settle, and long enough for you to judge it honestly.
Why does it cost what it does?
Because of what is intentionally included in each sachet. Eight actives, each at a named dose, with the botanicals as standardised extracts, so every sachet carries the same measured amount as the last. Every batch of material that goes into it comes with a Certificate of Analysis, and it is made in a BRCGS AA-graded facility: the food safety standard UK supermarkets require of their suppliers, at its top grade.
Can I take it with medication, or while pregnant?
Serune is not recommended during pregnancy or breastfeeding, and is not suitable for children. If you take any medication or are under medical supervision, speak to your doctor or pharmacist before taking any food supplement. To check a specific ingredient, email us, and we will answer directly.
Is there melatonin in it?
No added melatonin and no added hormones. That was a deliberate decision, not an omission.
How much caffeine is in it?
Very little. Cacao is in the formula for flavour, not as an active ingredient, in a small amount, so you get the rich, not-too-sweet taste without much of what comes with it. Cacao naturally contains theobromine and a trace of caffeine, and we do not add any on top of that. If you are sensitive to either, email us and we will send you the exact figures.
How do I store it, and how long does it keep?
Somewhere cool and dry, out of direct sunlight. The best-before date is printed on every pack.
When will my order arrive?
Pre-orders are dispatched from Monday 16 November 2026.
Once we are shipping, UK orders placed before 2pm on a working day are dispatched the same day, and after that the next working day. Standard delivery is Royal Mail Tracked 48 and usually arrives 2–3 working days after dispatch. It is free on orders of £35 and over, and always free on a subscription; below £35 it is £1.00.
At checkout you can upgrade to Priority (£1.97, Royal Mail Tracked 24, usually next working day) or DPD (£4.97, next working day with a one-hour delivery window and the option to redirect or leave safe).
Outside the UK, delivery is calculated at checkout and typically takes 5–10 working days in Europe and 7–14 working days elsewhere.
Why am I paying now for something that ships in November?
Because it is currently open only for pre-order as our first batch is still in the process of production. You are charged today (to lock in your pre-order pricing), we’ll dispatch from 16th November onwards, and you can cancel any time before it ships for a full refund.
Can I cancel a subscription?
Yes, at any time, in your account, in one click. No minimum term, no notice period, no phone call, no hidden charges. And if you have any further concerns, you can just reach out to us.
What if it is not for me?
Tell us within 30 days of your first pack arriving, and we will refund it. You keep the remainder of the pack. You won’t need to send anything back or fill in long forms to justify.
Where can I read the research behind the doses?
On the science page: every active, the amount in a sachet, the form we use and why, the published studies each dose was set against, and every authorised claim in full. https://www.serune.co.uk/pages/science
What exactly is in a sachet?
Eight actives in every sachet: saffron (Safr'Inside™) 30 mg extract standardised to ≥3% crocins; glycine 3,000 mg; magnesium 150 mg elemental as fully reacted, chelated magnesium bisglycinate; L-theanine 200 mg from green tea extract; lemon balm 400 mg leaf extract standardised to 7% rosmarinic acid; chamomile 400 mg extract standardised to 3% total apigenins; vitamin B6 2.8 mg as P-5-P; and zinc 10 mg elemental as zinc citrate, in a real cacao base with a Montmorency tart cherry note and Madagascar vanilla. There is no melatonin, no ashwagandha and no proprietary blend: every dose is on the label.
Is the saffron the same as in the studies?
Yes. Serune uses Safr'Inside™, the extract used in the two 2025 saffron sleep trials (Sleep Medicine: X, and the University of East Anglia), at the dose those trials used: 30 mg, which is the amount in one sachet. What the trials looked at, in the people they looked at, is on the science page.
What kind of magnesium is in Serune, and how much?
150 mg of elemental magnesium per sachet, as fully reacted, chelated magnesium bisglycinate. Elemental is the figure that matters: 150 mg of magnesium comes from roughly 1,150 mg of bisglycinate. That is 40% of the UK Nutrient Reference Value, so Serune is high in magnesium, and it is under the 250 mg a day supplemental ceiling. Magnesium contributes to a reduction of tiredness and fatigue and to normal psychological function.
Is the L-theanine natural?
Yes. Serune's L-theanine is extracted from green tea leaf (Camellia sinensis), the form with a history of use as a food. L-theanine made by chemical synthesis or fermentation is treated as a novel food and is currently going through authorisation; Serune does not use it.
What does "dosed to the research" mean?
For each active we found the form the human studies used and the amount they used, and matched it where the sachet allows. Glycine is 3 g because that is the dose in every human sleep study of glycine; saffron is 30 mg because that is the dose in the Safr'Inside™ trials; L-theanine is 200 mg because that is the dose in most of the human research; chamomile is 400 mg because that is the dose in the four-week sleep-quality trial. Where a trial used more than we do, the science page says so.
Which health claims can Serune legally make?
UK law only lets a food supplement make health claims that have been authorised. Three of Serune's eight actives hold authorised claims: magnesium, vitamin B6 and zinc, including "magnesium contributes to a reduction of tiredness and fatigue", "vitamin B6 contributes to the reduction of tiredness and fatigue" and "zinc contributes to normal cognitive function". Saffron, glycine, L-theanine, lemon balm and chamomile carry no authorised claim; we include them at researched doses and print exactly how much of each is in every sachet. The full list of authorised wordings is on the science page.
Is Serune tested?
Serune is made in the UK in a BRCGS AA-certified facility, the food safety standard the supermarkets audit against, at its highest grade. Every batch of material comes with a Certificate of Analysis, so the standardisation on the label is measured, not assumed. Serune contains none of the 14 declarable allergens and is gluten-free.
Why hot milk?
Because it makes the better drink and it is the ritual most people already keep. Serune makes no claim for milk, and hot water works too.