What Is the Caffeine Window?
Caffeine can be useful, enjoyable, and deeply personal. It can also remain in the body longer than the feeling of a drink lasts. Caffeine Window helps you place your usual caffeine earlier in the day by combining your habits, wake time, target bedtime, latest Sleep Score, and the drinks you record.
It shows when a suggested window is open, how much room remains in that window, and how much caffeine the model estimates may remain by your target bedtime. It is a planning tool—not a measurement of caffeine in your blood and not medical advice.
What the Caffeine Window can show you
Depending on the shape of your day, AIVELA can create:
- a First Window earlier after waking;
- a Second Window later in the day when timing and sleep context support one;
- a Cutoff before your target bedtime;
- an approximate amount available in the current window, shown in milligrams and whole servings of your primary drink when possible;
- a curve based on the caffeine you actually log today;
- an estimate of caffeine remaining at your target bedtime;
- a separate simulation of your typical caffeine habit.
The window is guidance, not a permission slip. You can always record a drink outside the suggested time or above the suggested amount. AIVELA saves what happened, updates the estimate, and provides light feedback without blocking the entry.
What shapes today's plan
Caffeine Window brings together five kinds of information:
- Your usual drinks and servings, which estimate a typical daily caffeine habit.
- Your primary drink, which turns milligrams into a more practical whole-serving comparison.
- Your target bedtime, which sets the day's Cutoff and bedtime-residual view.
- Your wake time, preferably detected from the ring, which positions today's windows.
- Your latest Sleep Score, which can shift more of today's suggested caffeine toward the earlier window after a poorer night.
Sleep Score changes the timing allocation; it does not make caffeine a treatment for poor sleep. If the score is unavailable, AIVELA uses its default timing plan. If you wake late, there may be only one safe planning window—or no remaining window before Cutoff.
Suggested allowance is not a target to finish
The amount displayed for a window is an approximate planning ceiling based on your selected habit and the available timing. It is not a recommendation to consume that amount, and unused allowance does not need to be “caught up” later.
Unused room in the First Window does not roll into the Second Window. If you consume more than planned early in the day, a later window can shrink or close. This keeps the later suggestion from growing simply because you skipped an earlier drink.
AIVELA uses the general healthy-adult reference of up to 400 mg per day as an outer planning boundary, not as a personal safety guarantee. Many people choose or need much less. Pregnancy, breastfeeding, medication, heart or liver conditions, anxiety, sleep problems, and individual sensitivity may call for different guidance.
A “cup” is only an estimate
Coffee and tea caffeine content varies with beans or leaves, brew method, serving size, recipe, extra shots, and preparation time. AIVELA's built-in drinks use general serving estimates. A medium café drink in the App cannot know the exact caffeine in the cup in your hand.
Milligrams are therefore the primary value. Whole servings are a convenience. If your usual drink differs meaningfully from the built-in estimate, create a custom drink using trustworthy label or manufacturer information.
What the curve means
After you log a drink, AIVELA estimates how its caffeine declines over time. Multiple drinks are added together, creating a curve for the caffeine you reported during the current wake-to-wake caffeine day.
The estimate uses a standard average decay model. Real caffeine metabolism varies substantially from person to person and can change with pregnancy, medication, smoking, liver function, and other factors. The curve is not a laboratory result, and “0 mg” in the model should not be treated as proof that caffeine has no effect on you.
The Today curve includes only drinks you recorded. It does not detect caffeine automatically, and the current version does not carry estimated caffeine across wake-to-wake cycles. Unlogged coffee, tea, energy drinks, chocolate, supplements, or medicines will not appear.
Habit estimate and today's curve are different
The detail page separates two views:
- Habit estimate: a simulation of your typical drinks placed within a typical day;
- Today's curve: an estimate built from today's actual caffeine logs and times.
Keeping them separate prevents a planned morning coffee from looking like one you already consumed. Before interpreting the bedtime estimate, check which view you are reading and whether today's record is complete.
When not to rely on the Caffeine Window
Caffeine Window is intended for adults who already consume caffeinated drinks. It is not designed to encourage a non-user to begin consuming caffeine.
Do not use it to determine a medically safe dose, manage pregnancy or breastfeeding intake, assess a drug interaction, or explain palpitations, anxiety, insomnia, or other symptoms. Follow local health guidance, product labels, and advice from a qualified professional.
If you experience a rapid or irregular heartbeat, severe agitation, vomiting, confusion, a seizure, or another serious symptom after substantial caffeine intake, seek urgent medical help or contact your local poison service.
Use the window to make timing more intentional—not to turn an estimate into a quota.