Quitting Coffee: What Caffeine Does to Your Nervous System

It is a little after eleven on a weekday morning, and the feeling arrives on schedule: a fog settling behind the eyes, the energy draining out for the rest of the day. For years, that was the rhythm of Conni Biesalski's workdays, one or two cups of coffee in the morning and a slump she never thought to question. In her July 2025 YouTube video, "I Quit Coffee 2.5 Years Ago and I'm Never Going Back," she reframes that ordinary ritual as something closer to a loan. Caffeine, she argues, produces an artificial stress response, borrows energy from later in the day, and can quietly amplify anxiety, digestive trouble, and sleep problems in people who never connect those symptoms to the cup on their desk.

What happened when she quit coffee cold turkey?

The experiment began almost casually. Biesalski told viewers she loved her coffee and didn't believe it was causing problems. "I was like, 'Nope, I'm good. I could quit at any point.'" When she decided to test that claim, she framed it as a 30-day challenge and asked her wife to join her, and the two of them stopped at once. That, she says plainly, was the mistake. "There's one thing that we did that I totally don't recommend. And that was quitting cold turkey. Not a good idea."

The withdrawal was severe for both of them. She describes daily headaches and a brain fog that rolled in after about 11 a.m., when her energy simply dropped for the rest of the day. She effectively wrote off a full week. What came after, she says, was a different kind of clarity: consistent energy through the day, better sleep, much better digestion, sharper focus, and a feeling of being more present. Her verdict on the whole ordeal is blunt. "It was pretty crazy actually."

The more unsettling part was what she noticed in hindsight. Looking back, she believes coffee had intensified her anxiety and her internal pressure. "I didn't know how much pressure and tension and anxiety I was carrying in my body until I quit caffeine." She had already dealt with digestive issues for years, and coffee made those worse too. The lesson she draws is not that coffee is uniquely dangerous, but that its normalcy hides its effects. "Drinking coffee is so normalized. It just never occurred to me that it could be bad for me."

Why does coffee feel like energy if it's borrowed?

The central claim of the video is that the energy coffee provides is not new energy at all. Biesalski puts it in a single line: "most of us assume that coffee gives us energy, but it's actually just borrowing it from tomorrow, which never works out in the long run." The idea is that when the body signals tiredness, the signal is information. A cup of coffee overrides it, and the fatigue does not vanish. It gets pushed forward, to the afternoon crash, to the night when sleep doesn't come easily, to the next morning's grogginess.

This is why she describes caffeine as overriding exhaustion, the freeze response, and the need to rest. Her point is not moralistic. It is physiological: the body has a language of tiredness, and caffeine silences it without answering the underlying need. Over time, she argues, that habit also loosens our connection to natural rhythms. We rise before the sun and activate ourselves with caffeine, or we push through deadlines and keep drinking coffee late into the evening, long after the body should be winding down.

What does caffeine actually do to the stress response?

Biesalski's central technical point is that caffeine produces what she calls an artificial stress response. The emphasis, she stresses, belongs on "artificial." Caffeine increases adrenaline and cortisol, which raises blood pressure and heart rate and speeds breathing, the same signs the body shows under real threat. "Caffeine mimics a stress response although there is no real stressor or threat present."

She offers a specific figure, attributed in the video to her own presentation: one cup of coffee can increase blood cortisol by 30 to 100 percent within an hour, and cortisol can stay elevated in the blood for up to 18 hours. That long shelf life matters. A morning cup is not a morning event; its chemical influence lingers into the evening, which is one reason sleep suffers. For someone whose nervous system is already running hot, she argues, the cup doesn't just add to the load. It can exacerbate a body that is already in a chronic stress state, and many people in that state have no idea they are there.

"So many people today are already in a chronic stress response. And many of us are not aware of that. Most of us aren't, right? because it's so normalized in our culture." (Conni Biesalski, "I Quit Coffee 2.5 Years Ago and I'm Never Going Back," July 2025)

How does coffee disrupt the daily cortisol curve?

The most useful visual in the video is the 24-hour cortisol curve, and it is worth understanding on its own terms. In a healthy rhythm, cortisol spikes in the morning, which is what gets us out of bed and moving. Then it declines through the day, bottoming out during sleep, before rising again at dawn. Biesalski presents this as what nature intends. The problem arises when the nervous system is already dysregulated and the body is producing more cortisol than it should, so that the morning peak runs into a second, caffeine-driven peak.

She also describes what she calls burnout, the opposite pattern. In that state, cortisol production can actually decline. But she frames this as the endpoint of a long process: the body has been overproducing cortisol for so long that it eventually fatigues. Chronic fatigue, in her model, is often not a sign that the system needs more stimulation. It can be the aftermath of too much of it.

Her clinical experience underpins the argument. She works with clients who have already seen other therapists and doctors for panic attacks, anxiety, digestive issues, and sleep problems, and she says that almost none of them were ever asked how much coffee they drank each day. When she helps them reduce caffeine, she says she often sees "incredible shifts within a week," because the adrenal system gets a break from constant stimulation. That is a claim from one practitioner's experience rather than a controlled study, and it is worth holding it as such. It is still a compelling reason to ask the question.

Why is coffee so hard to question?

Biesalski opens her video with a provocation that she returns to throughout. "Coffee is the most acceptable drug in the world." She cites the statistic that 90 percent of adults worldwide consume caffeine daily, which makes it the most popular psychoactive substance on earth. "The coffee plant really won," she says, and she is pointing to how thoroughly the habit has been woven into work, social life, and identity.

That normalization is precisely why the effects go unexamined. Nobody thinks to report that a morning coffee might be contributing to their panic attacks, because coffee is what everyone does. Her approach is to replace judgment with curiosity. "I'm not going to shame you for consuming coffee," she says, and she is careful to present her ideas as insights rather than commandments.

How can you cut back without the withdrawal crash?

Biesalski's own experience is the cautionary tale: go slowly. She still enjoys decaf, which tells you her position is about caffeine, not the ritual of a warm cup. Her practical guidance includes stopping coffee at a set cutoff time, which she gives as 1 p.m. in the context of protecting sleep. She also suggests tracking your sleep with a wearable device such as a ring or wristband, so you can see the effect of your choices rather than relying on how you feel. She mentions cacao as an alternative she enjoys, and she suggests paying attention to what the drink does for you beyond caffeine, including flavor and ritual.

Equally important is what happens in the evening. Biesalski describes the typical modern night as a sequence of stimulation: checking messages, watching Netflix, reaching for wine or sugar. Her argument is that caffeine and these habits all keep the nervous system activated, and that moving into a proper parasympathetic state, the rest-and-digest mode that the body needs, requires deliberately creating space for it. Quitting caffeine, in her framing, is less about removing one substance and more about restoring a rhythm.

What is the shadow work hiding behind the cup?

The video ends its most personal thread with a question rather than a rule. When you reach for coffee, what are you actually craving? For Biesalski, the answer she points toward is the need for rest, for relief from pressure, for a body that feels safe enough to slow down. The coffee is the most socially acceptable answer to a deeper want. "There's some shadow work for you," she says, inviting viewers to look at the habit as information rather than a failing.

That is the real takeaway of the video. It does not claim that coffee is poison, and it does not ask anyone to quit by a certain date. It asks a smaller and more radical question: what is this cup doing for me, and what is it costing me later? For a woman who once thought she could quit at any time and then found out how hard it was, the honest answer turned out to be a 2.5-year decision that she has no plans to reverse.

Where to go from here

If this resonated, start with the question Biesalski returns to most often: what does your body say when it feels tired, and what happens when you silence that signal with caffeine? Notice the time of your last cup and how your sleep and afternoon energy respond. If you decide to cut back, consider a gradual reduction rather than the cold-turkey approach she describes as a mistake, and give yourself time to get through the withdrawal window. Her full video, linked on her YouTube channel, goes further into tips for reducing caffeine and keeping coffee without the side effects, and it is worth watching in full if you are a daily drinker. Treat her specific numbers as the speaker's own figures, and bring the broader question to your own experience.