Sleep Depth Curve: What Caffeine Does to Deep Sleep | Reincarn Science Lab Skip to content

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Sleep is not one thing.
It is built in layers.

Most people judge a night by how many hours it lasted. Your brain judges it by how deep those hours went. This explains the difference, then lets you see what your own day of caffeine did to it.

The Night, Read as Brainwaves

Sleep stages are defined by rhythm, not by feel

Each stage is set by the speed of the electrical rhythm running across the surface of your brain, measured in hertz. As you descend, that rhythm slows down and grows taller. Each trace below is animated at its real relative wavelength.

Frequency bands and defining waveforms follow standard sleep scoring criteria. Stage percentages from Physiology of Sleep Stages, StatPearls / NCBI. Traces are stylised representations of each band, not recorded brain data.

A Typical Night, Drawn Out

Five cycles, and the deep ones come first

Deep sleep front loads. Your first cycle holds the most of it, and every cycle after holds less. That is why when you drink matters more than how much. Read the line against the labels on the left: every dip down to N3 is a stretch of deep sleep.

Five cycles, about 90 minutes each. N3 is the deepest stage and it front-loads into the first half of the night; REM, the dreaming stage, stretches longer toward morning. Above N3 sit N2 (core sleep), N1 (lightest) and wake. The dashed rings mark each run of deep sleep and its length.

That is the typical night. Now see yours.

Place your drinks on a timeline and watch what they do to your first cycle of deep sleep. Takes about a minute.

Questions and Myths

Six things people get wrong about sleep

Every answer carries its source. Tap to open.

Why You Might Not Be a Morning Person

Your body keeps its own clock, and it may not agree with your alarm

Everyone has a natural sleep and wake timing they drift into when nothing forces them otherwise: the hours their body would choose on a free week with no alarm. For some people that window sits early. For others it sits late, and it is partly inherited rather than chosen. Most people who wake up foggy every workday conclude something permanent about themselves. The research points somewhere less fixed, and far more fixable.

Worth knowing. Natural timing is real and partly genetic. Some people genuinely run late and always will, and morning people certainly exist. What the research adds is that grogginess tends to get filed under identity when a large share of it is sleep debt, timing mismatch and sleep depth. Those three move. Identity does not, which is why it is worth knowing which one you are actually dealing with.

Updates live 0 drinks · 0 mg — place a drink to begin

What You Drank, and When

Build your day, one drink at a time

Pick a drink, then tap the timeline to place it. Tap an existing drink to remove it, or drag it to a new time. Times snap to the nearest 15 minutes.

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Or add without the timeline:

The time you go to bed 11:00 pm

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Total you drank

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At lights out

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Across first cycle

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Still there at 3am

Your Sleep Depth Curve

What your first ninety minutes of sleep looked like

Your night A typical night

Place a drink to draw your curve.

The vertical axis is depth as a percentage of a full cycle. Solid gold is your night; the dashed line is the same night without caffeine, and the shaded band is the plausible range around it.

How do I read this?

The filled gold shape is how deep your sleep goes across the first 90 minutes after you fall asleep. It rises because you sink down into deep sleep, then falls as you come back up toward lighter sleep and dreaming. That rise and fall is completely normal and happens every night, with or without caffeine.

The dashed line above it is the typical night from the previous page: the same shape with no caffeine in your system. The gap between the two is the part your drinks are responsible for.

Only the first 90 minutes are shown, because that is where the effect lives. This is your deepest stretch of the night, and the one the research found caffeine actually touches.

This shape is illustrative. It shows the direction and pattern of the relationship measured by Baur 2024 and Landolt 1995, anchored to the 100 mg at bedtime condition those studies actually tested.

Your Deep Sleep ReportNot yet generated

Optional Refinement

Make your curve more accurate

Your curve already works on population averages. These two questions tune it to how your body handles caffeine: how fast you clear it, and how strongly you react to what is left. They are independent of each other.

Do any of these apply to you?

These change how quickly caffeine leaves your body. All facts, nothing to guess at. Tick everything that applies, or leave it blank.

Think of the last time you had caffeine within about 6 hours of bed.

Coffee, chai, cola, an energy drink, anything. What happened that night?

You have optimised everything. Except this.

Caffeine is only one of the thieves.

You just saw what a single day of coffee does to your deepest sleep. Caffeine is the easiest thief to see. It is not the only one. Late screens, a mind that will not switch off, an inconsistent bedtime, and stress flatten that same first cycle, night after night. It is why you can do everything right and still wake up at 70%.

Protect it. The best deep sleep you will get is free. Last caffeine by early afternoon, screens down before bed, and a consistent wake time. Start there. Most of the gap you just saw closes with timing alone.

Support it. When you have protected it and still wake up unrecovered, that is where Reincarn Night Reboot comes in. A melatonin-free, clinically-dosed formula designed to support deeper sleep across the full cycle. Its deep-sleep ingredient, Maizinol, has been shown at our dose to add up to 30 minutes of deep sleep and reduce cortisol by up to 36% (Talbott, 2023).* It works alongside good sleep habits, not instead of them.

Five questions, about a minute. See where your sleep is breaking down, and which of the thieves is taking your mornings.

Stay current with the science of sleep and performance

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* +30 minutes of deep sleep refers to outcomes from a double-blind, placebo-controlled clinical study of Maizinol UP165™ at 250mg (Talbott SM et al., 2023, PMC9889011). Individual results may vary. This claim pertains to the Maizinol UP165™ ingredient and not to the REINCARN Night Reboot™ formula as a whole, which has not been tested in a single combined clinical trial.

This content is for informational purposes only and does not constitute medical advice. These statements have not been evaluated by the Food Safety and Standards Authority of India (FSSAI). Reincarn Night Reboot is a food supplement and is not intended to diagnose, treat, cure, or prevent any disease. For adults 18+. Contains KSM-66 Ashwagandha; consult a healthcare professional before use, especially if you have a thyroid condition or take medication.

Not ready for that?

What Actually Affects How Long Caffeine Stays Within Your Body

Clearance. The rate at which your body breaks caffeine down and removes it from your blood.

Almost all of the caffeine you drink is broken down by one particular enzyme in your liver. Think of it as a single doorway that every cup has to pass through on the way out. Anything that widens that doorway clears caffeine faster; anything that narrows it leaves caffeine sitting in you for longer. The average person halves their caffeine in about 5 hours, but the honest range across healthy people runs from roughly 1.5 hours to 9.5, before any of the things below are added on top. [source]

What	Effect	Why it happens	Source
Smoking or vaping nicotine	Clears about twice as fast	Smoke widens that doorway considerably. It is the single biggest everyday reason two people react differently to the same coffee.	NCBI
Hormonal birth control pill, patch, ring or injection	Roughly twice as long	Oestrogen narrows the doorway. A five hour clearance commonly stretches to eight or ten, and it is strongest in the second half of the monthly cycle. Very few people know this about themselves.	NCBI
Pregnancy	Up to 15 hours	The doorway narrows steadily as pregnancy progresses, and by the final months a single afternoon coffee can still be with you the next morning.	Ann Epidemiol
Some antidepressants fluvoxamine in particular	Five to eleven times longer	The most dramatic effect anyone has measured. In two controlled studies caffeine clearance went from about 5 hours to 31 in one, and from 5 to 56 in the other. If you take this medication, ordinary caffeine advice does not apply to you.	1996 · 2005
Some antibiotics ciprofloxacin and relatives	Noticeably longer	Narrows the doorway while you are on the course. Worth knowing if a week of antibiotics suddenly comes with bad sleep.	2024 review
The genes you were born with	Fast or slow, from birth	The largest natural cause of difference. Some people are simply built with a wider doorway than others, which is why your friend can have coffee after dinner and sleep like a stone.	Clin Transl Sci
Liver conditions	Substantially longer	The doorway is in the liver, so anything affecting liver function affects caffeine directly.	NCBI
Broccoli, cabbage and similar vegetables	Slightly faster	Genuinely widen the doorway a little in controlled feeding studies. A real effect, but a small one. Not a reason to change your dinner.	Carcinogenesis
Charcoal grilled food	About 14% faster on average	Also widens it, but the individual response ranged from 29% slower to 147% faster across people in the study. Too unpredictable to plan around.	Hum Exp Toxicol
Age	Slower at the extremes	Newborns clear caffeine extremely slowly. In healthy adults the effect stays modest until other things stack on top of it.	Review 2021

The part almost everybody gets wrong

How fast you clear caffeine and how strongly you feel it are two different things.

One set of genes decides how long caffeine stays in you. A completely separate one decides how hard your brain reacts to whatever is there. Roughly one in eight people carries a version of that second gene which makes caffeine disrupt their sleep noticeably more, at exactly the same amount in the blood. [source]

So you can clear caffeine perfectly normally and still sleep badly on it, or clear it slowly and barely notice. That is why the calculator asks you two separate questions: the first sets how fast your curve falls away, the second sets how much a given amount actually costs you in sleep depth.

Worth saying plainly: on an identical dose, the amount of caffeine circulating during sleep varied roughly ninety fold between people in one controlled study. That gap is bigger than almost anything in the table above. [Baur 2024]

See what yours does

Tick the ones that apply and get your own number.

References

Every source, and exactly what it contributed

Everything in this tool traces back to one of the sources below. Each row states not just what the source found, but specifically what it was used for here, so nothing has to be taken on faith. Last reviewed 12 August 2026.

Source	What it contributed here
Landolt et al., 1995 Neuropsychopharmacology	Established that caffeine specifically reduces low-frequency delta activity, the EEG signature of deep sleep. Direct basis for modelling caffeine as suppressing sleep depth rather than sleep in general.
Baur et al., 2024 Journal of Sleep Research	Measured how plasma caffeine concentration relates to EEG delta power, and the roughly ninety-fold person-to-person variation in circulating caffeine on an identical dose. Anchors the depth-suppression curve and the “two separate things caffeine changes” explanation.
Drake et al., 2013 Journal of Clinical Sleep Medicine	Tested caffeine taken 0, 3 or 6 hours before bed and measured the resulting sleep disruption. Supports the core premise that timing, not just amount, changes the outcome.
Pharmacokinetics of caffeine, 2021 Frontiers in Pharmacology, systematic review	Source for the average ~5 hour half-life and the 1.5–9.5 hour honest range used as the model's baseline before any personal factors are applied.
Pharmacology of Caffeine Institute of Medicine / NCBI Bookshelf	General reference for how nicotine, liver function and hormonal contraception change caffeine clearance. Basis for several rows in the clearance-factors table.
CYP1A2 genotype study, 2019 Clinical and Translational Science	Documents genetic variation in caffeine clearance speed. Basis for describing “the genes you were born with” as a clearance factor.
ADORA2A and sleep PMC	Shows a separate gene governs sensitivity to caffeine's sleep-disrupting effect, independent of clearance speed. Direct basis for asking two separate questions instead of one.
Jeppesen et al., 1996	First controlled measurement of fluvoxamine's effect on caffeine clearance, roughly 5 to 31 hours. Basis for the medication clearance-factor entry.
Culm-Merdek et al., 2005 British Journal of Clinical Pharmacology	A second, independent measurement of the fluvoxamine effect, roughly 5 to 56 hours. Used alongside Jeppesen 1996 to keep that factor's estimate conservative.
Antibiotic interaction review, 2024	Basis for including ciprofloxacin and related antibiotics as a clearance-slowing factor.
Kall & Clausen, 1996 Carcinogenesis	Basis for the small, genuine clearance speed-up from broccoli and similar vegetables noted in the clearance table.
Kall & Clausen, 1995 Human & Experimental Toxicology	Basis for the charcoal-grilled food clearance note, including the wide individual variation flagged alongside it.
Grosso & Bracken, 2005 Annals of Epidemiology	Basis for the pregnancy clearance multiplier, and the explicit caution that pregnancy needs different guidance than this tool provides.
Chou & Bell, 2007 Journal of Food Science	HPLC-measured caffeine content of major soft drinks. Source for the Coca-Cola, Diet Coke, Pepsi and Pepsi Black figures, rescaled to Indian can and bottle sizes.
FSSAI standards for caffeinated beverages	Indian regulatory caffeine caps. Every beverage figure in the drink list was checked against this, so each one is legally possible in India, not just plausible.
Monster Energy 350 ml India label Open Food Facts	The actual Indian product label, used to correct an earlier US-sourced figure that had overstated Monster's caffeine content by about 50%.
Physiology, Sleep Stages StatPearls / NCBI Bookshelf	Standard reference for sleep-stage frequency bands, stage percentages and the natural front-loading of deep sleep. Basis for the wave cards and the hypnogram.
Chronotype and social jetlag, 2025 Scientific Reports	Basis for the “not a morning person” section's discussion of workday sleep debt and schedule mismatch.
Morning sleep inertia study PLOS One	Basis for the roughly 16-minute average duration of morning grogginess described in the “not a morning person” section.
Starbucks caffeine guide Caffeine Informer, cross-checked against Starbucks' own figures	Cross-check for the six Starbucks brewed and latte figures, all three sizes, against Starbucks' published nutrition data.
USDA FoodData Central	Reference composition database used to sanity-check tea and Indian coffee preparation values, including the smaller tapri and cup servings.

Sleep is not one thing.It is built in layers.