How to use Heda

Overview

Heda is an offline-first headache and migraine diary for Android. All health data is encrypted and stored only on your device. Nothing is uploaded to any server — your data is yours alone.

The app has four main areas, accessible from the bottom navigation bar:

Getting started

Sign in

Heda requires a Google account to protect your data. Signing in creates an encrypted, device-bound key linked to your account — no data is stored in the cloud.

1. Open Heda after installing it from Google Play.
2. Tap Sign in with Google and choose your Google account.
3. Your account is now bound to this installation. The same Google account must be used if you reinstall the app.

First-run consent

On first launch, Heda asks whether you want to share anonymous crash reports. This does not send any health data. You can change your choice later in Settings → Privacy & Data.

• Anonymous crash reports — automatically reports crashes so bugs can be fixed quickly (GlitchTip). No usage analytics are collected.

Calendar

The Calendar is your daily view. It shows the current month at a glance, with coloured dots indicating headache intensity on each day.

Month view

The month strip at the top shows the current month in an ISO-week grid (weeks run Monday–Sunday). Each day that has at least one logged event shows a small intensity dot:

• ● Blue — intensity 1–3 (mild)
• ● Red — intensity 4–5 (severe)

Use the ‹ and › buttons to navigate between months. Tap any date to select it and see that day's events below.

The current date is highlighted. Tapping the Today label or today's date scrolls back to the current day.

Event cards

Events for the selected date are shown as cards below the month strip. Each card displays:

• The headache type (Headache or Migraine)
• Time range — start and end time, and the duration
• An intensity bar (1–5 scale)
• Aura and rescue medication indicators, if logged

Tap a card to open it in edit mode where all fields can be changed.

Quick Add

For fast logging, tap Quick Add at the bottom of the Calendar screen. A sheet slides up with the most essential fields:

• Type — Headache or Migraine
• Intensity — slider 1–5
• Aura — checkbox
• Rescue medication — checkbox

Tap Save to log immediately using the current time, or tap Add details… to open the full event form pre-filled with these values.

Logging an event

To log a new event with full details, tap the + Add event button in the Calendar. If you tapped a specific date first, that date will be pre-selected in the form.

Type & intensity

Choose between Headache and Migraine using the selector at the top. Then set the intensity on a scale of 1 (mild) to 5 (incapacitating) using the slider.

Date & time

Three fields control the timing of the event:

• Date — tap to open a date picker. Defaults to today.
• Start time — when the attack began. Tap to open a 24-hour time picker.
• End time — when the attack ended. Defaults to 2 hours after the start time. If you move the start time past the end time, the end time advances automatically to maintain the 2-hour gap.

Pain area

The 3D head model lets you mark exactly where the pain is located. It supports two gestures:

• One finger — paint pain areas by dragging across the surface of the head.
• Two fingers — rotate the head to reach areas at the back, sides, or neck.

Eight anatomical regions are supported:

Enable the Colour-code by intensity toggle to tint the painted regions with the intensity colour (light red for mild, deep red for severe). This is off by default.

Possible triggers

Record potential triggers that may have contributed to this attack. They are grouped into seven categories:

Aura & rescue medication

• Aura — tick if this event was preceded by an aura (visual disturbances, tingling, speech changes, etc.).
• Rescue medication — tick if you took acute medication (e.g. a triptan, NSAID, or paracetamol) during this attack.

Notes

The free-text notes field captures anything not covered by the structured fields — context, observations, what helped, or any other detail you want to remember.

Tap Save when done. The event appears on the Calendar immediately.

Editing & deleting events

Editing an event

1. Navigate to the date in the Calendar.
2. Tap the event card you want to change.
3. The event form opens in edit mode — all fields are editable.
4. Make your changes, then tap Update to save.

Deleting an event

1. Open the event in edit mode (tap its card in the Calendar).
2. Scroll to the bottom and tap Delete entry.
3. A confirmation dialog appears. Tap Delete to permanently remove the event.

Analysis

The Analysis screen has two tabs at the top: Statistics and Correlations. Statistics is available to all users. Correlations is a premium feature that also requires a Health Connect connection.

Statistics

The Statistics tab gives you an overview of your headache frequency and severity across a selected time period.

Period selector

Choose between five time periods:

Summary card

A hero card shows the following metrics for the selected period. Trend arrows (↑ / ↓) compare each figure to the equivalent previous period:

Charts

• Trend chart — event count per time bucket (daily for 7/30/90 days, weekly for 1 year, monthly for All time).
• Weekday heatmap — shows which days of the week your headaches occur most often.

Type breakdown & triggers

A stacked bar shows the split between event types (Headache / Severe Headache / Migraine / Severe Migraine) with counts and percentages. Below it, a horizontal bar chart lists your most frequent triggers for the selected period.

Correlations

The Correlations tab analyses your Health Connect data and looks for nine evidence-based patterns that commonly precede headache and migraine attacks. It looks back over the last 90 days.

Your baseline

A baseline card at the top shows your 14-day median values for each health metric. A "—" is shown for any metric without sufficient data.

• Sleep — median nightly total sleep duration
• HRV — median heart rate variability (ms)
• Resting heart rate — median resting heart rate (bpm)
• Steps — median daily step count
• Exercise — median daily active minutes
• Deep sleep — median nightly deep sleep duration
• REM sleep — median nightly REM sleep duration
• Awake during sleep — median awake time within sleep sessions

Detected patterns

Heda checks nine evidence-based patterns for each headache event. Each finding shows the measured value and the threshold it crossed — for example: "Slept 5 h 30 min before this event (threshold: 7 h)".

• Short sleep — total sleep the night before was less than 7 hours (configurable in Settings → Advanced).
• Irregular sleep schedule — sleep timing varied by more than 120 minutes (std. dev.) over the preceding 7 days.
• Low step count — fewer than 3 000 steps the day before the event (configurable).
• HRV drop — HRV fell below 30 ms or below 80 % of your 14-day personal baseline.
• Elevated resting heart rate — resting heart rate was above your 14-day median the day before the event.
• Exercise spike — active minutes were unusually high compared to your 14-day median the day before.
• Low deep sleep — deep sleep was well below your 14-day median the night before.
• Low REM sleep — REM sleep was well below your 14-day median the night before.
• Fragmented sleep — awake time within sleep sessions was unusually high relative to total sleep and your baseline.

Recommendations

Based on the detected patterns, Heda generates personalised recommendations ranked by priority (High / Medium / Low). Examples include improving sleep duration or regularity, increasing daily activity, or managing stress and recovery.

Reports

The Reports tab lets you view structured summaries of your data and export it for sharing with a healthcare professional.

Monthly report

The monthly report shows a calendar view for each selected month, with each day colour-coded by status:

• No events — no attack recorded
• Headache — at least one headache event
• Migraine — at least one migraine event

A pie chart shows the proportion of days in each category. Select one or more months using the month chips. Tap Select all or Clear to quickly select or deselect all months.

Daily report

The daily report focuses on individual events within a selected period. Choose from:

A summary row at the top shows total events, average intensity, and the date range. Below it, each event is listed with its type, time, and intensity.

Exporting data

Use the export buttons to save your data:

• Export as CSV — saves a comma-separated file with all events in the current period. Columns: Date, Time, Type, Intensity, Aura, Rescue medication, Triggers, Notes. The Android system file picker lets you choose the save location.
• Export as PDF — generates a formatted PDF document with the summary and event table, suitable for printing or sending to a doctor.
• Export Health Connect data as CSV — optionally export the cached sleep, heart rate, HRV, step count, and exercise data alongside your headache events.

Settings

Access Settings from the bottom navigation bar. Changes take effect immediately.

Theme

Choose between three options:

• Light — warm paper-toned light mode.
• Dark — deep forest dark mode (default).
• System — follows your device's dark/light mode setting automatically.

Language

Choose from 30+ languages grouped by region (Nordic, Germanic, Romance, Slavic, Baltic, and Other). The selected language applies to all text in the app. Choose System to follow your device's language setting.

Health Connect

Links to the Health Connect settings screen where you can grant or revoke permissions for sleep, heart rate, HRV, steps, and exercise data. See the Health Connect section for details.

Privacy & Data

Opens the Privacy & Data screen where you can manage your account, review what data is stored, exercise your GDPR rights, and delete your data. See the Privacy & Data section for details.

Automatic Health Connect sync

When enabled, Heda fetches your latest health data from Health Connect once per day in the background, even when the app is closed. This is off by default. Enabling it requires Health Connect permissions to be granted.

Daily health recommendations

When enabled, Heda sends a daily notification if a high-priority correlation is detected. Tapping the notification opens the Analysis screen. This is off by default and requires the device's notification permission.

Advanced

Expand the Advanced section to fine-tune the thresholds used by the correlation engine. The defaults match established clinical guidelines for migraine prevention:

Tap Reset to defaults to restore all thresholds to their original values.

Privacy & Data

Open Settings → Privacy & Data to manage all data and account settings.

Your account

The top of the screen shows the Google account currently signed in. Tap Sign out to sign out of the app. Your data remains on the device; you can sign back in at any time.

What data is stored

All data is stored locally on your device in two encrypted databases:

Encryption keys are stored in the Android Keystore, hardware-backed where available, and never leave the device.

Biometric lock

Enable biometric lock to require a fingerprint, face unlock, or PIN to open the app. Requires a screen lock to be configured in device Settings.

Diagnostics

Optionally share anonymous crash reports (GlitchTip). No health data is ever included. No usage analytics are collected. This can be changed at any time.

Your GDPR rights

Heda complies with EU GDPR Article 9 (special categories of personal data). Your rights:

• Right of access (Art. 15) — all your data is visible in Calendar and Statistics.
• Right to rectification (Art. 16) — edit any event by tapping it in the Calendar.
• Right to erasure (Art. 17) — delete all data via the Danger zone (see below).
• Right to restriction (Art. 18) — sign out to stop all processing.
• Right to data portability (Art. 20) — export all events as CSV from the Reports screen.
• Right to object (Art. 21) — sign out; processing stops immediately.

Danger zone

• Delete local data (keep account) — permanently deletes all headache records, health data, settings, and encryption keys from this device. Your Google account link is kept, so you can sign in again on any device.
• Delete account and all data — permanently deletes everything above plus your Supabase account. There is no recovery. A two-step confirmation is required.

Health Connect

Health Connect is Google's unified health data platform for Android. Heda reads five types of health data from it to power the Correlations feature on the Analysis screen:

Setting up Health Connect

1. Go to Settings → Health Connect in Heda.
2. If the Health Connect app is not installed, tap Install Health Connect to get it from Google Play. (Android 9 and later. On Android 14+, Health Connect is built in.)
3. Tap Connect Health Connect.
4. In the Health Connect permission screen, grant Heda access to Sleep, Heart rate variability, Heart rate, Steps, and Exercise.
5. Return to Heda. Your recent health data will be displayed.

Background sync

By default, health data is only fetched when you open the Health Connect screen or tap Refresh. Enable Automatic Health Connect sync in Settings to fetch data once per day in the background.

Revoking access

You can revoke Heda's Health Connect permissions at any time in the Health Connect app (Manage apps & devices → Heda → Permissions) or in Settings → Health Connect inside Heda. Previously cached data remains on your device until you delete it via Privacy & Data → Delete local data.