How to Use the Caffeine Window
The Caffeine Window is most useful when it reflects your real routine. Set a realistic target bedtime and typical caffeine habit, then record each drink with its actual time and approximate milligrams. AIVELA will update today's timing status, current-window suggestion, decay curve, and estimated bedtime residual.
You do not need to follow the window perfectly. Its job is to help you make a more informed choice—and to keep the record honest when you choose differently.
1. Set up a realistic caffeine habit
Start with:
- your target bedtime;
- the caffeinated drinks you typically have;
- the number of whole servings you usually drink in a day;
- one primary drink for the App's whole-serving comparisons.
Choose what a normal day looks like, not the most caffeinated day you can remember. AIVELA uses the selected drinks to estimate your typical intake and simulate what may remain at target bedtime.
Built-in drinks use standard serving estimates. Actual caffeine varies with recipe, cup size, brew method, extra shots, and preparation. If your usual drink has reliable label or manufacturer information that differs meaningfully, create a custom drink with its caffeine per serving.
2. Read the Today card from top to bottom
The Today card is intentionally compact. It brings together:
- Sleep and wake context — how the latest sleep result and today's start shaped the plan.
- Time status — whether a window is upcoming, open, ending soon, or finished.
- Dose status — the approximate amount still available in the relevant window, or a light notice that the plan is nearly used or exceeded.
- Today's chart — timing windows first, then a decay curve after you record caffeine.
- Log caffeine intake — the action for adding what you actually consumed.
The card does not ask you to finish an allowance. “Up to” and “remaining” describe a planning ceiling, not a daily goal.
3. Understand the First Window, Second Window, and Cutoff
The First Window appears earlier after waking. A Second Window may appear later when enough time remains before your target bedtime. Cutoff marks the point after which AIVELA no longer recommends additional caffeine for that plan.
A poorer Sleep Score may move more of the suggestion into the earlier window and remove the later one. It does not increase the total plan or imply that caffeine replaces sleep.
If you wake late, the available day becomes shorter. AIVELA may offer only one reduced window or no active window rather than push caffeine closer to bedtime.
Unused First Window allowance does not move into the Second Window. Skipping a morning drink is not a reason for the afternoon suggestion to grow.
4. Log what you actually drank
Tap Log caffeine intake, then review:
- time, which defaults to now but should match the actual intake;
- drink, selected from the built-in or custom list;
- milligrams, prefilled from the serving estimate but editable for this intake.
Save the record even if it was outside a window or above the suggestion. AIVELA will keep the event, update the curve and remaining guidance, and may add a light “Caffeine exceeded” context Tag. It does not block or shame the choice.
Remember to include caffeine from tea, matcha, cold brew, energy products, chocolate, supplements, or medicines when relevant. The ring does not detect caffeine automatically.
5. Correct mistakes instead of compensating for them
The detail page lists today's caffeine records in time order. You can edit an incorrect time or dose and delete a record that did not happen. Each change recalculates the current estimate.
Do not add a second fake entry to correct the first one. Edit the original so dose totals, Timeline context, and the decay curve stay aligned.
If an early intake used more than planned, the Second Window may shrink or close. If you delete or reduce that record, the later status can update again.
6. Do not confuse the two curves
The detail page separates:
- Habit estimate, a simulation based on the routine in your settings;
- Today's curve, based only on the drinks and times you logged today.
Before the first real intake is logged, today's chart shows the windows but no caffeine-decay curve. This prevents a planned drink from looking like one already consumed.
The current model starts a new caffeine day when you wake. It does not carry yesterday's modeled residual into today's curve, so the display is not an estimate of every trace that may remain in your body.
7. Use the bedtime number for comparison
“Estimated at bedtime” applies a standard five-hour half-life model to the doses you recorded. Use it to compare choices: the same drink earlier versus later, or one drink versus two.
Do not treat it as:
- a blood caffeine measurement;
- a guarantee of sleep quality;
- a personalized metabolism test;
- confirmation that a dose is medically safe;
- a complete estimate when records are missing.
People clear and feel caffeine differently. Pregnancy, medicines, smoking, liver function, and other factors can materially change caffeine metabolism.
8. If today's plan looks wrong
Check these inputs first:
- Is the target bedtime current?
- Did the ring synchronize today's wake time?
- Is the wake time shown as estimated?
- Does the primary drink match what you usually consume?
- Are today's drink times and milligrams complete?
- Did a late wake leave too little time before Cutoff?
Update settings or records when the facts are wrong. If the facts are right but the suggestion does not feel appropriate, follow your own sensitivity and professional guidance rather than forcing yourself to use the available amount.
9. Keep health guidance separate from the model
Caffeine Window is for adults with an existing caffeine habit. It is not intended to encourage caffeine use or determine a medically safe dose.
The general healthy-adult reference used by the planning model is not appropriate for everyone. Pregnancy, breastfeeding, medication, caffeine sensitivity, sleep difficulties, and health conditions can require lower or different limits. Follow local guidance and advice from a qualified healthcare professional.
Log honestly, compare timing, and leave any unused allowance unused.