Ireland runs on tea. We are, year after year, among the biggest per-capita tea drinkers on the planet, and the kettle going on is still the first response to good news, bad news and no news at all. Coffee has muscled its way in alongside it, and between the two most of us are taking a fair dose of caffeine every day without ever thinking of it as a drug.
It is one, though, and it is worth a second look after 50. Not because tea and coffee are bad for you (the evidence is, on balance, rather encouraging), but because the way caffeine interacts with your sleep, your bladder, your bones and your medicines can shift as the years go on. Here is what the research actually says, and what it means for your morning routine.
TL;DR
- European food safety guidance puts a sensible ceiling at around 400mg of caffeine a day for healthy adults, roughly four mugs of brewed coffee or six to eight mugs of tea.
- Caffeine’s effect on sleep tends to feel stronger after 50, because sleep becomes lighter and more easily disrupted with age. A cut-off of eight hours before bed suits most people.
- Tea with a meal can reduce iron absorption significantly, which matters if you are prone to anaemia. Leave an hour either side.
- Coffee interferes with levothyroxine absorption, and bisphosphonates for osteoporosis must be taken with plain water only.
- Moderate coffee and tea drinking is associated with lower rates of type 2 diabetes, Parkinson’s disease and liver disease. There is no need to give it up for the sake of it.
What actually changes with age
The popular belief is that older bodies clear caffeine more slowly, so it lingers and keeps you awake. The reality is more interesting. The liver enzyme that breaks caffeine down, CYP1A2, holds up reasonably well for most people into later life. What changes more is the sleep itself.
From our 50s onwards, sleep naturally becomes lighter, more fragmented, and shorter in its deepest restorative stages. Caffeine works by blocking adenosine, the chemical that builds up through the day and creates the pressure to sleep. When your sleep is already more fragile, blocking that pressure has a bigger practical effect. The dose has not changed. Your margin has.
The Irish Longitudinal Study on Ageing has consistently highlighted how common sleep difficulty is among adults over 50 in Ireland, and caffeine is one of the few contributing factors entirely within your own control.
How much are you actually drinking?
Most people underestimate this considerably. Rough figures for a standard mug:
- Filter or brewed coffee: 100mg to 140mg
- Instant coffee: 60mg to 80mg
- Espresso (single shot): 60mg to 80mg
- Black tea: 40mg to 75mg, depending heavily on brewing time
- Green tea: 30mg to 50mg
- Cola: around 30mg per can
- Energy drinks: 80mg or more per 250ml
The European Food Safety Authority considers up to 400mg a day from all sources safe for healthy adults, with single doses up to 200mg. Note that a strong cup of tea left to stew properly can rival a coffee. It is the brewing time, not the leaf, that does most of the work.
Do not forget the quiet contributors either: some cold and flu remedies, certain painkillers and a few migraine preparations contain caffeine, and dark chocolate carries a modest amount.
Sleep: the cut-off that actually works
Caffeine has an average half-life of about five hours, but the range across individuals runs from two to more than eight. A well-known sleep study found that 400mg taken six hours before bed still cost participants over an hour of sleep, and crucially, they did not notice. Their subjective sense of how well they had slept barely registered the loss.
That is the trap. If you are convinced coffee at four o’clock has no effect on you, the objective measurements may disagree. A practical approach: set your last caffeinated drink at around eight hours before bed, hold that line for two weeks, and judge by how you feel in the morning rather than by how quickly you fall asleep.
Heart, blood pressure and rhythm
Caffeine causes a short-lived rise in blood pressure, typically 5mmHg to 10mmHg, and it is most pronounced in people who drink it rarely. Regular drinkers develop substantial tolerance to this effect. Large population studies have not found habitual coffee drinking to be a cause of long-term hypertension.
If you are having your blood pressure checked, skip the coffee for 30 minutes beforehand so the reading reflects your baseline rather than your breakfast.
On atrial fibrillation, the received wisdom has softened considerably. Older advice told anyone with AF to cut out caffeine entirely. More recent evidence does not support moderate coffee as a trigger for most people, and some studies suggest a neutral or even slightly protective association. That said, some individuals genuinely do notice palpitations. If you are one of them, trust your own pattern and discuss it with your GP or cardiology team.
Bones, iron and the bladder
Three practical points that come up often.
Bones. Very high caffeine intakes (well above 400mg) modestly increase the amount of calcium lost in urine. This only becomes meaningful if your calcium intake is low to begin with. Interestingly, tea drinking is associated with better bone density in several studies, likely thanks to its flavonoids. A splash of milk in your tea offsets most of the concern anyway.
Iron. This one deserves more attention than it gets. The tannins in tea can reduce the absorption of non-haem iron (the type found in vegetables, pulses and fortified cereals) by more than half when taken with a meal. If you have been told you are anaemic or borderline, keep tea to an hour before or after eating rather than alongside it.
Bladder. Caffeine is a recognised bladder irritant and a diuretic. If urgency, frequency or getting up repeatedly at night is bothering you, reducing caffeine is one of the first things a continence adviser will suggest, and it often makes a noticeable difference within a fortnight.
Medication interactions worth knowing
If you take regular medication, a few genuine interactions are worth flagging:
- Levothyroxine for an underactive thyroid: coffee markedly reduces absorption. Take it with plain water and wait 30 to 60 minutes before your first cup.
- Bisphosphonates such as alendronate for osteoporosis: plain water only, on an empty stomach, staying upright for 30 minutes. Tea or coffee will render the dose largely useless.
- Ciprofloxacin and some related antibiotics slow caffeine clearance, meaning your usual intake hits considerably harder.
- Theophylline for respiratory conditions shares a metabolic pathway with caffeine and effects can stack.
Your community pharmacist can run through your full list in a few minutes, and it is free. Ask at your next repeat prescription.
The good news, and there is plenty
None of the above is an argument for giving up. Observational research consistently links moderate coffee and tea consumption with lower rates of type 2 diabetes, Parkinson’s disease, several liver conditions and all-cause mortality. Tea and coffee are among the largest sources of polyphenols in the Irish diet, and they contribute to your daily fluid intake despite the persistent myth that they dehydrate you. The mild diuretic effect does not outweigh the water in the cup.
There is a social dimension too, and it is not trivial. The cup of tea is the pretext for the conversation, the visit and the check-in. That matters for wellbeing in ways no nutrient panel will capture.
If you do want to cut back
Go gradually. Stopping abruptly produces genuine withdrawal: headache, irritability and fogginess that peak roughly a day or two in and can last a week. Reduce by about a quarter every few days, swap one cup at a time for decaf (which retains the polyphenols and the ritual), and start with the latest cup of the day rather than the first. Most people find the morning cup is the one they actually want, and the four o’clock one is pure habit.
The bottom line
For most adults over 50, moderate tea and coffee are a genuine positive. The adjustments worth making are timing rather than quantity: earlier in the day, away from your levothyroxine, and not alongside an iron-rich meal. If sleep, bladder symptoms or palpitations are troubling you, a two-week trial of an earlier cut-off costs nothing and tells you more about your own body than any study can.
At Críonna Health, we believe good information should be practical enough to use before your next cup goes cold. For more evidence-informed guidance on ageing well in Ireland, explore our other guides on sleep, nutrition and medication safety.
This article is for general information and is not a substitute for personalised medical advice. If you have concerns about caffeine, sleep or your medication, speak to your GP or community pharmacist.
📷 Photo by Krišjānis Kazaks on Unsplash
