Paracelsus' poison

Paracelsus' poison

Should over 50’s avoid that afternoon coffee? Maybe.

Coffee, one of our favourite sources of caffeine. Ian Musgrave

Sleep is good. This is one thing both experts and the person in the street can agree on about that knitter up of the unravelled sleeve of care [1]. Getting decent sleep not only leaves you feeling refreshed, but lack of good quality sleep is associated not just with fatigue and lower life quality, but can also increase the risk of diseases such as Alzheimer’s and type II diabetes.

Sadly, as we age we are less likely to get good sleep, we sleep less deeply than when we were younger, wake more and are more likely to be disturbed in our sleep. Recently the Global Council on Brain Health (GCBH) published 20 recommendations that would help people over 50 years of age to have better sleep.

Now in reporting this did the newspapers focus on the recommendations to not drink alcohol three hours before bed time, keeping mobile phones and tablet devices out of the bedroom or keeping pets out of the bedroom?

No, they focused on the recommendation to avoid caffeine after lunch time, with headlines such as “Sleep tips: Avoid afternoon coffee, over-50s advised” and “Middle aged and want a good night’s sleep? Don’t have a cuppa after lunch”.

Well, that’s disappointing, I like my afternoon cuppa

Yes, as does my Mum and thousands of Australians rich in years.

The advice is sensible though. After all, caffeine is a stimulant, and who amongst us has not used strong coffee to try and stave off sleep. Ironically enough, moderate coffee consumption is associated with lower risks of Dementia and type II diabetes.

The effects of caffeine can persist some time, taking 400 milligrams of caffeine can cause you to lose up to an hours sleep and have to have more disturbed sleep up to six hours after you have taken it.

But, you are going to say “But …” aren’t you

But, 400 milligrams of caffeine is roughly the equivalent of chugging four espressos at once, and is the maximum recommended daily caffeine intake. And you really shouldn’t consume more than 300 milligrams in one go.

A typical afternoon cuppa will have between 50-100 milligram caffeine, depending on whether it is tea or coffee, instant or brewed. This is 1/8th to ¼ the amount used in the sleep study. Here are some representative levels of a variety of caffeinated beverages per typical serve.

375 ml Iced Coffee: 68 mg caffeine
Average espresso:   75-85 mg Caffeine
Instant coffee:   ~ 65 mg Caffeine
Tea:                50-80 mg caffeine
Colas:              30- 70 mg caffeine
Energy Drinks:      80-160 mg caffeine

Now, you won’t drink 400 milligrams of caffeine in one hit usually, people typically have between 2-4 cups per day. This makes calculating the amount of caffeine in your body a little tricky, as the amount present in your body accumulates to different levels depending on how often you drink it.

Simulations I have run suggest that the level of caffeine in your body six hours after consuming 400 milligrams of caffeine (the amount that can lose you an hour of sleep) is a bit under the maximum amount of caffeine in your body after consuming 100 milligrams of caffeine [2].

Bllod levels of caffeine simulated after one 400 mg dose of caffeine (top line) or three 100 mg doses taken every three hours (bottom line) Ian Musgrave

If you drink you last caffeinated drink with 100 milligrams of caffeine in it at 4 pm, then you need to wait around four hours for the caffeine levels to fall below the levels associated with the loss of one hours sleep, make it six hours to be safe and if you have had a beverage with 100 milligrams of caffeine in it at 4 pm, you should be going to bed at 10 pm (or put it another way, if you want to go to bed at 10pm, you last caffeinated drink with 100 milligrams caffeine should be at 4 pm).

Of course I have calculated these values based on the average amount of time it takes the body to absorb caffeine and break it down.

You are going to say “It’s complicated” now, aren’t you

Well, yes. The amount of time peoples bodies take to break down caffeine is roughly 4 hours on average, but this can vary from as little as 2.5 hours to as much as 9 hours. This can produce huge differences in the amount of caffeine in the body (roughly three fold between the slowest and fastest rate of breakdown.

As well, the pathways in the brain that are responsible for the stimulant effect of caffeine can vary in sensitivity.

So you can have someone like me who can drink espresso late at night with no apparent effect on sleep, and my partner, who cannot drink a cup of tea after 3 pm without having disturbed sleep.

So what about age, which is the whole point of this

As you age, your body’s ability to break down drugs and natural products is reduced.

However, it turns out that caffeine is not affected; in fact older folk break caffeine down slightly faster than young people. But they also absorb it more slowly, so the effects basically cancel out and older people and young people have very similar levels of caffeine after consuming it.

On the basis of caffeine concentrations alone, the recommendation to avoid caffeine after lunch is being a little over cautious [3].

On the other hand the brain systems that caffeine interacts with to cause stimulation alter with age, and this may make older people more sensitive to caffeine’s effects.

What is the bottom line then?

Getting good sleep is about more than cutting out tea and coffee after lunch.

The Global Council on Brain Health has suggested several approaches to improving sleep quality, so that you can get about 7- 8 hours of sleep in a 24-hour period.

These include not drinking alcohol three hours before bedtime (this recommendation will disturb my in-laws most), not eating or drinking generally for three hours before bed [4], getting regular exercise, getting more outdoor light exposure, losing weight if you are overweight, having a regular bedtime routine and not having smart phones and tablet devices in the bedroom at night as the screens light is distracting.

Avoiding (NOT do not drink tea or coffee at all all) caffeine is sensible advice as part of a coordinated approach to better sleep. Slamming back double espressos late at night is guaranteed to disturb your sleep, but an afternoon cuppa is unlikely to bother you (unless of course you are caffeine sensitive).

Be sensible, use a coordinated approach to the recommendations rather than fixating on one thing and hopefully you will sleep better.

[1] Sleeping in the street is not recommended.

[2] These are simplistic simulations, using the data on caffeine breakdown by young and old men from https://www.ncbi.nlm.nih.gov/pubmed/6886969 Comparative pharmacokinetics of caffeine in young and elderly men and assuming you drink 100 milligrams of caffeine at 10 am, 1 pm and 4 pm.

[3] The recommendation to avoid caffeine after lunch has been widely misinterpreted as to mean having no caffeinated beverages after lunch.

[4] As I write this a large part of Australia is in the grip of a massive heat wave, keeping hydrated, especially for older people, is essential in the conditions, so make sure you are getting plenty of fluids even at night.

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