Friday Tidbits #10: Coffee & Cortisol

Welcome to Friday Tidbits. This is a very short email with morsels of information to help you tweak your life and health for optimum longevity and healthy ageing.

19 January 2024

Stress, Sleep & Breathing

A simple breath protocol can help to fall asleep

Since early December my sleep has not been ideal. We are in the process of buying a new house. They say buying a house is one of the most stressful life events alongside death and divorce! REF????

I both struggle to fall asleep and wake at 2am. This is called onset insomnia and maintenance insomnia respectively. Many of you will have experienced on or the other at some point. Not fun.

When I wake at 2am, I can feel my heart beating in my chest. It feels much faster then it should be. I am also aware of my rapid breath rate. Next time you are in this situation, try to pay attention to your breath rate.

Trying to calm my racing thoughts and fall back to sleep I have been using a very simple breath protocol. And no, box-breathing is unlikely to help in situations of heightened stress. The protocol is an even cadence for 1-2 minutes, followed by resonance cadence on repeat. Until hopefully I fall asleep.

Breath protocol: 10 breaths of 4 count inhale and 4 count exhale (4-4) and followed by 4 count inhale and 6 count exhale (4-6).

To be honest, this did not work every time. Sometimes I would fall sleep - for what feels like minutes before waking again. At the minimum, the focus on my breath helps to quite my racing mind.

Coffee and Cortisol

People who regularly drink coffee in the morning have similar cortisol levels to those who do not.

Few things have so many myths and half-truths than coffee and caffeine. Last week I overheard a conversation where it was stated that your early morning coffee negatively affects your hormones. And that eating before coffee will prevent this effect.

Where to begin to unpack this? Which hormones exactly? And by what mechanism is it impacted? And should you even care?

The hormone in question is cortisol. Cortisol is also referred to as the stress hormone and many people believe it is not a good things. But cortisol is your friend (sometimes your frenemy), without it you will not wake up in the morning. Cortisol helps to regulate energy balance, giving you a lift when you need it during the morning and help to slow down later in the day¹.

The Hypothalamus in the brain monitors (all) hormone levels to make sure it is in the right balance at any particular point in time. It sends a signal to the Pituitary gland (also in the brain) which sends another signal to the organs that secrete more or less of the active hormone. The organs in this case are the Adrenal glands located on top of the kidney. This is called the HPA-axis. Cortisol is secreted in a daily cycle called the circadian rhythm, with the lowest point around midnight, rising around two hours before waking, peaks early morning and then slowly decline over the day (Figure 1).

Figure 1. Cortisol and melatonin levels over a 24-hour period. Cortisol is lowest in the middle of the night and peaks early morning before slowly declining during the day. Image created in Biorender.

People with an abnormal cortisol rhythm can struggle to fall asleep and have low energy in the morning. This may indicate HPA-axis dysfunction often due to stress (see above). Addison’s disease is a condition where not enough cortisol is produced. It is a very serious disease referred to as adrenal insufficiency and required glucocorticoid replacement therapy on a daily basis. Fortunately, this is a very rare condition. On the opposite side of the spectrum, chronically high cortisol levels can indicate a disease called Cushing’s syndrome - again a very rare condition. As mentioned, stress and elevate cortisol levels above normal or disrupt the normal rhythm. This is associated with depression and poor cognitive function and can take a long time to correct.

Cortisol release is one of the mechanisms that help to feel energised and motivated. very helpful is you are sleep deprived. Caffeine (from any source) does stimulate the secretion of cortisol by elevating the production of adrenocorticotropic hormone (ACTH) secreted by the pituitary gland (Lovallo et al. 2005).

The study

Lovallo et al. (2005) conducted an interesting study to test the effect of habituation to caffeine and cortisol levels of 96 men and women. Cortisol levels were measured under three different coffee ingestion habits. For 5 days participants consumed either 0mg, 300mg or 600mg of caffeine in capsule form daily. The caffeine was split into three doses taken at 8am, 1pm and 6pm. On the 6th day, a challenge caffeine dose of 750mg (3 x 250mg) was consumed and cortisol levels compared (Table 2).

Table 2 from Lovallo et al. (2005). Placebo and caffeine doses on study weeks. Control group PP with no caffeine, different caffeine intake levels of 0mg, 300mg and 600mg per day for 5 days each followed by a challenge dose of 750mg per day.

Under all three conditions, caffeine concentration measured in saliva after the 2nd dose at 1pm increased by nearly 30% above the peak of the first dose (Figure 2). Caffeine is not cleared (fully metabolised) from the body by 1pm and more than half of the caffeine ingested at 8am is still detectable. In real life, your 2nd cup of coffee at midday, increases your total caffeine concentration and hopefully your alertness. By 6pm caffeine concentration will be the same as after your 1st cup in the morning. Not surprisingly, many people might struggle to fall asleep.

Figure 2. Caffeine levels under different challenge conditions compared to the control. The control (PP) has no ingestion of caffeine, the dashed line PC show caffeine levels with the challenge dose of 750mg after a period of no ingestion. Two different maintenance levels of 300mg (dotted line C300) and 600mg (dash-dot line C600) per day preceded the challenge day of 750mg. Regular ingestion of caffeine leads to a higher total concentration with the challenge, indicating that not all the caffeine has been metabolised from the previous day. From Lavollo et al. 2005.

The cortisol results are a bit tricky to interpret. Referring to figure 3, the solid line (PP) is the control arm of the study and show the baseline cortisol with 0mg caffeine. The normal expected cortisol values are observed with the highest level early morning, followed by a slow decline during the day. Cortisol values jumped mid-morning after a mentally stressful activity.

The top line (long dashes PC), show the cortisol on the challenge day of 750mg after 5 days of no caffeine. This represents the effect of caffeine on people who do NOT regularly consume coffee. Cortisol values were significantly higher during the day at all times measured. Compared to the other conditions, the stress challenge midmorning induced a much higher spike in cortisol. If you never drink coffee and then drink a single coffee, your body’s stress response is heightened under conditions of stress compared to no caffeine.

The effect of habituation to caffeine was tested with 300mg and 600mg per day. The dotted line C300 and dot-dash line C600 show the respective cortisol values on the challenge day of 750mg. For both levels, cortisol levels are not significantly higher compared to the control during the morning.

However, drinking a cup of coffee midday will raise cortisol levels significantly above baseline for the remainder of the day. Good news, by 7pm (one hour after the last cup), cortisol levels are nearly the same as the control side.

Figure 3. Cortisol levels in saliva on 4 test days after maintenance of either 0mg, 300mg or 600mg. Solid line PP is the control with no caffeine challenge. The dashed line PC show caffeine challenge of 750mg after a period of no caffeine. Dotted line C300 show the effect on cortisol with the challenge dose after a maintenance habit of 300mg per day and the C600 show the cortisol levels with the challenge dose after a maintenance of 600mg daily dose. From Lovallo et al. 2005.

From the above data the conclusion can be made that the desired cortisol spike from coffee may not be achieved if you consume coffee when your cortisol levels are naturally high in the morning. This exclude the performance enhancing effect that caffeine will have on performance.

There is little evidence that eating before your morning coffee will blunt the effect on cortisol. Caffeine is absorbed in the stomach and small intestine and reach peak blood levels in 20 minutes².

What does this all mean?

• If you regularly drink a single coffee early in the morning, cortisol levels will be almost the same as when you don’t drink coffee. Your body adapts and there is minimal negative effect for most people.

• Caffeine do not acutely elevate cortisol levels in the absence of stress.

• A stress event will spike your cortisol levels briefly.

• The stress-induced spike is more pronounced with caffeine if you do not regularly drink coffee.

• A midday coffee will increase cortisol and alertness during the afternoon.

• Cortisol levels for many people will likely return to normal by the time you go to sleep.

• Genetics determine your rate of caffeine metabolism. Some people might struggle to fall asleep when they consume caffeine after midday.

• I have not been able to find research evidence to show that eating food before drinking coffee 1st thing in the morning will blunt the cortisol effect.

• Exercise and food will increase cortisol levels independent of caffeine and the effect appears to be different between men and women (more on this in future).

If you want to get the most of your coffee, drink it around mid-morning when your cortisol levels are falling. This will give you the required energy lift.

References:

1. Lovallo WR, Whitsett TL, al'Absi M, Sung BH, Vincent AS, Wilson MF. Caffeine stimulation of cortisol secretion across the waking hours in relation to caffeine intake levels. Psychosom Med. 2005 Sep-Oct;67(5):734-9. doi: 10.1097/01.psy.0000181270.20036.06. PMID: 16204431; PMCID: PMC2257922 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2257922/

2. Nieber K. The Impact of Coffee on Health. Planta Med. 2017 Nov;83(16):1256-1263. doi: 10.1055/s-0043-115007. Epub 2017 Jul 4. PMID: 28675917.