Caffeine suppresses cerebral grey matter responses to chronic sleep restriction

Medical engineer here; I would suggest anyone whoms interest was caught by the title to read the Discussion, not Abstract. The authors have made good use of the section to broaden their conclusions, answering some of the questions I've observed in this thread.

For anyone starting to second-guess their relationship to sleep and caffeine; do note that this is a small-sample study and that more research is needed before any conclusions can be drawn with regards to the population at large.

EDIT: I'm not a medical professional (i.e a Doctor), I'm simply an engineer with domain knowledge in medicine. I am accustomed to reading studies like this. If anyone needs help interpreting the study, I'm happy to assist.

I love my caffeine. But caffeine is an addictive, highly profitable substance. So advertising it and trying to promote it as somehow having real health benefits is widespread.

I would not be surprised if routine consumption of caffeine was at least mildly detrimental to health.

I think some drugs have managed to gain a special place in our society . Advertising and lobbying warps our perception of these drugs.

I even saw a comment in this thread suggesting that if caffeine has a prolonged affect on you, then you have some unique genetics and it's essentially your problem, not the drug. Similar to the narrative about alcohol. It's interesting to compare that attitude to the way illegal drugs that can't advertise or lobby are viewed.

I like caffeine. It's fun to drink a cup of tea or coffee once in a while and feel an extra surge of productivity.

What I don't like is that it has encouraged the grind of people working far longer and harder than they should for no reason except economic gain which is fundamnetally unsustainable. When people feel tired, they should take a break, and not develop a habit of drinking caffeine every day to keeep going. It's an unhealthy society and reinforces the message that economic gain is important above all else.

Anyone with anxiety or sleep issues should reexamine their caffeine usage. Maybe those problems do not stem from caffeine, but maybe they do. I don't know many people that do not consume caffeine regularly, at least once a day - in such cases, you cannot know whether your anxiety, sleep problems, general tiredness, bad moods, ... are or are not caused by one's caffeine consumption.

Some people swear by drinking a shot of espresso right after dinner, claiming that they can "sleep just fine" (or that it even calms them). It's not whether you can or cannot fall asleep, it's how deep and restorative your sleep is that is important here.

Side topic, but dropping coffee was the best thing I ever did. I used to drink only one cup a day, rarely two, for many years - but turns out when I stopped (for reasons unrelated) my anxiety unexpectedly 80% went away after a week or so without any other changes in my lifestyle. It was a big difference and I feel now very different than what I used to. I wake up much better rested too (much easier to get out of bed). Too bad, I really loved the taste but it's not worth it for me.

I encourage anyone to give it a try a few weeks and see how they feel. You may not realize what you thought is your baseline is in fact caused by caffeine sensitivity. I heard of some people being sensitive to caffeine but I never thought it would affect me, after all I did not have that bad of a reaction but it really built up and I had gotten used to it.

Recently I've learned that half of the people are slow caffein metabolizers. The caffein stays longer in their system and it might negatively affect their sleep. Considering how many people drink coffee, I think a lot of people are affected by this.

Caffeine, up to a certain daily dose, is associated with long-term cognitive benefits and a reduced risk of dementia.

This study hints that it specifically doesn't benefit gray matter volume during periods of sleep restriction, at least in the short term.

I wonder if substances like Ashwagandha extract or Magnesium L-threonate could mitigate gray matter loss during short term sleep restriction among caffeine drinkers.

I am growingly convinced that coffee/caffeine hit people in very different ways. https://www.23andme.com/topics/wellness/caffeine-consumption... has a few fun citations to look through on this, but discussions of how varied we are with how it impacts us is ridiculously invisible in most discussions of it.

Sleep is similar. We speak of "night owls" and such, but most discussion around the varied needs of sleep are age targeted. With most discussion on how we should let kids sleep longer.

On a cultural note regarding the threads, the moralistic make do with what god gives you side and the yay drink coffee and do stuff and be happy side have been around a long time. A little Bach Cantata about a grumpy old dad and his coffee drinking daughter: https://youtu.be/nifUBDgPhl4?feature=shared

Am I wrong to conclude from the abstract that sleep deprivation + caffeine = reduction in grey matter?

Abstract:

> Evidence has shown that both sleep loss and daily caffeine intake can induce changes in grey matter (GM). Caffeine is frequently used to combat sleepiness and impaired performance caused by insufficient sleep. It is unclear (1) whether daily use of caffeine could prevent or exacerbate the GM alterations induced by 5-day sleep restriction (i.e. chronic sleep restriction, CSR), and (2) whether the potential impact on GM plasticity depends on individual differences in the availability of adenosine receptors, which are involved in mediating effects of caffeine on sleep and waking function. Thirty-six healthy adults participated in this double-blind, randomized, controlled study (age = 28.9 ± 5.2 y/; F:M = 15:21; habitual level of caffeine intake < 450 mg; 29 homozygous C/C allele carriers of rs5751876 of ADORA2A, an A2A adenosine receptor gene variant). Each participant underwent a 9-day laboratory visit consisting of one adaptation day, 2 baseline days (BL), 5-day sleep restriction (5 h time-in-bed), and a recovery day (REC) after an 8-h sleep opportunity. Nineteen participants received 300 mg caffeine in coffee through the 5 days of CSR (CAFF group), while 17 matched participants received decaffeinated coffee (DECAF group). We examined GM changes on the 2nd BL Day, 5th CSR Day, and REC Day using magnetic resonance imaging and voxel-based morphometry. Moreover, we used positron emission tomography with [18F]-CPFPX to quantify the baseline availability of A1 adenosine receptors (A1R) and its relation to the GM plasticity. The results from the voxel-wise multimodal whole-brain analysis on the Jacobian-modulated T1-weighted images controlled for variances of cerebral blood flow indicated a significant interaction effect between caffeine and CSR in four brain regions: (a) right temporal-occipital region, (b) right dorsomedial prefrontal cortex (DmPFC), (c) left dorsolateral prefrontal cortex (DLPFC), and (d) right thalamus. The post-hoc analyses on the signal intensity of these GM clusters indicated that, compared to BL, GM on the CSR day was increased in the DECAF group in all clusters but decreased in the thalamus, DmPFC, and DLPFC in the CAFF group. Furthermore, lower baseline subcortical A1R availability predicted a larger GM reduction in the CAFF group after CSR of all brain regions except for the thalamus. In conclusion, our data suggest an adaptive GM upregulation after 5-day CSR, while concomitant use of caffeine instead leads to a GM reduction. The lack of consistent association with individual A1R availability may suggest that CSR and caffeine affect thalamic GM plasticity predominantly by a different mechanism. Future studies on the role of adenosine A2A receptors in CSR-induced GM plasticity are warranted.

I haven't seen this mentioned in the comments yet, so I'll mention it here. For the last year, I've seen health pundits (Huberman, etc.) recommend delaying caffeine intake for two hours after waking, for the purpose of allowing adenosine to clear from the brain first.

Ever since I've adopted this strategy, I find myself avoiding a mid-morning crash, and generally feeling more alert in the mornings. I wonder if the deleterious impact on grey matter could be mitigated in part by delaying consumption until fully awake.

Ease Up on the Espresso: If your sleep isn’t great lately, consider cutting back on the caffeine. Turns out, chugging coffee during sleep-deprived stints might shrink grey matter in parts of your brain. Not ideal if you’re trying to keep that brain in tip-top shape.

Know Your Limits: Everyone’s different when it comes to coffee tolerance. This study found that how your brain reacts to caffeine can depend on your genes—specifically, something about adenosine receptors. So, pay attention to how much caffeine you can handle, especially when you’re short on shut-eye.

Catch Those Zs: Don’t skimp on recovery sleep. After a brutal week, make sure to get some solid, uninterrupted sleep to bounce back. It helps counteract the rough effects of those sleepless nights and may even undo some of the caffeine-induced brain changes.

An interesting article to read, would love to see a larger samples size at some point. I am also going to continue drinking my mid-day espresso, morning coffee, and afternoon pick me up caffeine drink...

>> Each participant underwent a 9-day laboratory visit consisting of one adaptation day, 2 baseline days (BL), 5-day sleep restriction (5 h time-in-bed), and a recovery day (REC) after an 8-h sleep opportunity.

Was this a vacation? Was this study done at a resort? During push times I aspire to 5-hour sleep times. Talk to anyone in any branch of the military. During any sort of active operation, 5-hours in bed is total luxury. Or fishers. Or cops. Or food service workers. Or doctors.

Caffeine does nothing for me at all, I do not get a kick when I drink coffee. It does not affect my sleep, it does not give me a boost at all. So I am a bit of jealous of those who can utilize caffeine for mental boost, I just drink it for the taste.

The important sentence from the abstract:

> In conclusion, our data suggest an adaptive GM upregulation after 5-day CSR, while concomitant use of caffeine instead leads to a GM reduction.

I'm not sure what to take away from that. It sounds bad, though.

Are any of these results applicable to a non sleep-restricted state?

The study was on 5 days of 5-hr sleep only. How does caffeine affect 8-hrs sleep?

Rule: if you drink (coffee) dot not stay awake.

I've sad it before, and I'll say it again: the human body is not meant to ingest any other liquid than pure, filtered water.