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.

A useful log can include an unplanned drink

A meeting runs late and you drink something outside the suggested window. Record the reality rather than hide it to keep the chart neat. The feature is there to make the pattern clearer, not to mark your choices right or wrong. Tomorrow's useful question may simply be whether another timing choice fits better.

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:

1. Sleep and wake context , how the latest sleep result and today's start shaped the plan.
2. Time status , whether a window is upcoming, open, ending soon, or finished.
3. Dose status , the approximate amount still available in the relevant window, or a light notice that the plan is nearly used or exceeded.
4. Today's chart , timing windows first, then a decay curve after you record caffeine.
5. 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. Use timing labels as references

The windows and Cutoff help you consider where a drink fits in the day. They are not a guarantee of unaffected sleep or a medically safe dose. If your schedule changes, check the current day and target bedtime rather than assuming yesterday's plan still applies.

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. Compare choices without treating the estimate as a test

The bedtime view offers an estimate from recorded intake. It may help you explore an earlier drink versus a later one. It cannot measure blood caffeine, establish personal metabolism or guarantee sleep quality.

Read it with the scope of the log and your experience. Missing drinks make the record incomplete, while a precise number cannot make the underlying estimate certain.

8. If today's plan looks wrong

Check these inputs first:

1. Is the target bedtime current?
2. Did the ring synchronize today's wake time?
3. Is the wake time shown as estimated?
4. Does the primary drink match what you usually consume?
5. Are today's drink times and milligrams complete?
6. 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.

Related reading

• What Is the Caffeine Window?
• How the Caffeine Window Estimates Caffeine Over Time
• What Is Calm?
• When Your Sleep Results Look Unusual