CircadiaLog

Sleep and circadian rhythm researchers running studies, from single-site student projects to multi-centre international collaborations. If your protocol involves sleep diaries, shift logging, EMA, or light exposure tracking, CircadiaLog is built for your workflow.

CircadiaLog is currently available by invitation only.

Get in touch with a brief summary of your study and what you need the platform for. We will set up your research group's environment within three working days. From there, everything is self-service: your Centre Admin manages studies, staff, and participants through the platform, supported by built-in documentation. Training sessions are available on request.

CircadiaLog is offered at cost, making it significantly more affordable than commercial alternatives. Pricing is discussed on a per-study basis depending on scale and duration. Get in touch to talk through your requirements.

Yes. Small-scale student projects without dedicated funding can apply to use the platform at no cost. We are always keen to support the next generation of sleep and circadian researchers, so if you are a student with a genuine interest in the field, get in touch with a brief description of your project and we will see what we can do.

CircadiaLog offers five independent data collection modules, each of which can be enabled or disabled per study: Sleep Diary (bed/sleep/wake times, quality, optional contextual questions); Event Diary (timestamped events such as caffeine, exercise, meals, medication, up to 12 custom types); Work Rota (shift start/end with automatic day/night classification); Light Exposure Diary (hourly H-LEA framework with 7 environment categories); and EMA Questionnaires (custom ecological momentary assessments with flexible scheduling).

Yes. CircadiaLog supports up to 10 study arms (e.g., intervention vs. control) and 20 study stages (phases). Study announcements, materials, and notifications can be targeted to specific arms or stages. Participants can be moved between stages with defined start and end dates.

Yes, extensively. Every aspect of the participant experience can be tailored to your protocol. For example, you can enable or disable individual sleep diary questions, define custom event types, control whether participants can view their own sleep history, and set how far back retrospective entries are allowed. Study documents can also be gated by study phase. If you are wondering whether a specific configuration is possible, get in touch.

Researchers design questionnaires using a visual builder with four question types: multiple choice (single or multi-select), Likert scales, and visual analogue sliders. Up to 20 questions per questionnaire. Pre-built templates are available for commonly used measures, such as SSS, PANAS etc, which can be used as-is or adapted to your protocol.

Three scheduling modes are available: fixed daily times, random prompts within a time window, or block-randomised schedules. Prompts are timezone-aware and delivered as push notifications. Each prompt has a configurable response window with an automatic reminder if the participant has not yet started.

For studies with a configured location, CircadiaLog automatically retrieves objective environmental data daily from the Open-Meteo archive, including sunrise and sunset times, photoperiod, cloud cover, sunshine hours, UV index, temperature, and weather conditions.

Environmental data is fetched using a study-level coordinate defined by the researcher, not the participant's device location. CircadiaLog does not collect or store participant location data at any point. This data requires no input from participants and is collected entirely by a background process.

It is included as an optional sheet in the study data export, allowing researchers to cross-reference sleep and light exposure records against objective environmental conditions on the same dates.

All metrics are calculated server-side from participant diary entries, ensuring consistency across dashboards and exports. Core sleep metrics include TIB, TST, Sleep Efficiency, SOL, WASO, sleep midpoint (MSFsc), social jetlag, catch-up sleep, and night-to-night variability (SD and RMSSD). Weekday and weekend splits are calculated automatically.

For shift-work studies, the analysis engine links sleep episodes to shifts, producing metrics by shift type, transition effects, quick returns, and consecutive night-shift runs. All time-of-day averaging uses circular means, handling midnight-crossing times correctly.

Per-participant dashboards give researchers access to compliance rates, data quality indicators, and trend visualisations without needing to export first.

CircadiaLog is available as native iOS and Android apps, with browser access also available as a fallback for participants who need it. Data syncs seamlessly regardless of how participants access the platform.

The Android app requires Android 7.0 or later (released 2016), covering the vast majority of active Android devices. The iOS app requires iOS 16 or later, compatible with iPhone 8 and newer devices (released 2017). Browser access works on any modern browser including Chrome, Safari, Firefox, and Edge.

Yes. CircadiaLog is designed offline-first. Participants can log sleep diaries, events, shifts, and light exposure entries without an internet connection. Entries are stored securely on the device and automatically sync when connectivity returns. The app has been designed to support extended offline periods of 40 days or more, suitable for remote fieldwork, expeditions research, or in areas with limited connectivity.

The participant-facing interface is currently English only, but the localisation infrastructure is fully built and ready for most major languages (except for Arabic and Hebrew). Adding a new language requires translating a single file with no code changes needed.

Researchers who need a specific language are welcome to contribute a translation themselves. All localisation contributions are credited. Get in touch if this is relevant to your study.

The participant interface is designed with accessibility as an ongoing consideration and aims to meet WCAG 2.1 Level AA standards. Specific measures include colour contrast compliance for all interactive elements in both light and dark themes, screen reader support with ARIA labels throughout the interface, keyboard navigation with visible focus states, and automatic reduction of animations for participants who have enabled reduced motion at the operating system level.

Yes, provided the research group has appropriate ethical approval and has obtained verifiable parental or guardian consent before enrolment, in accordance with applicable law (COPPA in the United States, GDPR Article 8 in the UK and EU, and local research ethics requirements). Because participant accounts are created by research staff, not through self-registration, CircadiaLog does not interact with minors directly; the research group handles the consent process outside the app using its own approved protocol.

Yes. GDPR compliance is built into the platform architecture, not bolted on as an afterthought. Participants can submit data access and deletion requests directly through the app with automatic 30-day compliance deadline tracking. When a participant withdraws, their personal identifiers are permanently removed while research data is preserved under an irreversible anonymous code, maintaining dataset integrity. Participants register with synthetic identifiers (e.g., oxford-P001), so no personally identifiable information is stored alongside research data. All staff actions are logged, archived after 60 days, and retained for 3 years. CircadiaLog operates as a Data Processor; your research group remains the Data Controller.

Your research group is the Data Controller. CircadiaLog operates strictly as a Data Processor, handling data only as instructed by your research group and in accordance with applicable data protection regulations. Data ownership remains with the research group at all times.

CircadiaLog uses a single sub-processor: Google Firebase for cloud infrastructure (database, authentication, file storage, hosting). All application data is stored in London (europe-west2) and no participant diary data leaves the Google Cloud infrastructure.

Two additional third-party external services support non-personal operational functions: Resend for transactional email delivery (staff email addresses only, never participant data), and Open-Meteo for weather and daylight data (study-level location coordinates only, never participant data).

All data is stored on Google Cloud infrastructure in the europe-west2 (London) region. Data is encrypted at rest using AES-256 and encrypted in transit using TLS. Data does not leave the UK or EU under any operational circumstance. No data is stored on third-party servers outside of Google's infrastructure.

CircadiaLog collects only what is necessary for the research protocol. Data collected includes diary entries (sleep, work rota, events, light exposure), EMA questionnaire responses, study phase and group assignments, and device push notification tokens if the participant grants permission. Notification schedules are also stored to manage prompt delivery.

No real-world personal identifying information is collected at any point. Participants are not registered with a name or email address. Each participant is assigned a study identifier by the researcher before enrolment, and this identifier is the only credential used within the platform.

CircadiaLog does not collect participant names, email addresses, phone numbers, or any other real-world identifying information. It does not collect device location or GPS data. It does not collect biometric data. It does not use cookies for tracking or advertising. It does not share any participant data with third parties for any purpose other than platform operation. It does not use participant data for any purpose beyond operating the platform on behalf of the research group.

Participants log in using a simple Login ID and password; no personal email address is required. The Login ID follows a centre-specific format (e.g., oxford-P001). Researchers create accounts and set initial passwords, which participants can change after first login. This approach supports pseudonymisation by design, as no real-world identity is captured in the login process.

CircadiaLog enforces strict data isolation through multiple layers: role-based access control with four access tiers (Centre Admin, Researcher, Project Manager, Participant); centre-level isolation enforced at the database level so staff in one research group cannot access another research group's data; study-level scoping so researchers only see data for assigned studies; and participant isolation so participants can only access their own entries.

Yes. Participants can submit data access or deletion requests directly from within the app. Requests are routed to centre administrators with automatic 30-day deadline tracking and email notifications. The platform provides a full workflow for staff to acknowledge, process, and complete these requests.

Yes. CircadiaLog maintains a comprehensive audit log covering over 40 action types, including participant creation, data exports, account deletions, GDPR request handling, and study configuration changes. Logs are archived after 60 days and retained for 3 years. Centre administrators can search, filter, and export audit records at any time.

No. CircadiaLog does not apply any AI or machine learning processing to participant data. All calculations (sleep metrics, shift classifications, etc.) use deterministic, published algorithms. Data is used solely for the purposes defined by each study.

The full privacy policy is available inside the app, at the bottom of the Settings screen. You can also read it on the web.

The participant's account and profile are permanently deleted, and all standing notification schedules are removed. Research records are anonymised: the participant identifier is replaced with a randomly generated anonymous code with no reverse-mapping. No identifying information is retained after withdrawal.

Upon study conclusion, all participant data associated with that study is permanently and irrecoverably deleted from the platform. This includes all diary entries, questionnaire responses, notification schedules, phase assignments, and study materials. Deletion is triggered manually by the research team in accordance with their ethics approval and institutional data retention policies.

Participant data is protected by two simultaneous backup mechanisms. Point-in-Time Recovery maintains a continuous version history at minute-level granularity over a rolling seven-day window, allowing recovery of any document at any specific minute within that period. Daily snapshots provide a longer-term safety net retained for thirty days. Backups are strictly an infrastructure recovery mechanism and are not accessible to researchers or participants.

Bulk study data exports as Excel (.xlsx) workbooks with separate sheets for each data type and a summary sheet. Individual participant exports (for GDPR data access requests) use NDJSON format. Analytics summaries can be exported as PDF reports.

Yes. Exports can be filtered by date range, study stage and study arm, specific participants (all or a selected subset), and data type (sleep diary, events, work rota, light exposure, environmental data). Each export includes a summary sheet with metadata: export date, study name, participant count, and record counts per data type.

CircadiaLog supports multiple notification types: Daily reminders at participant-chosen times, delivered as native device notifications; EMA prompts with automatic 15-minute follow-up reminders; Scheduled notifications timed relative to each participant's personal schedule; and On-demand messages sent by researchers through the Notification Centre.

Researchers can define up to 5 time anchors per study, named reference points tied to each participant's daily routine (e.g., "Wake Time", "Bedtime", "Meal Time"). Notifications are then scheduled relative to these anchors (e.g., "Wake Time + 50 minutes"). Each participant's anchor times are personalised, so notifications arrive at the right moment for each individual, even across different time zones.

Yes. Researchers can send push notifications to individual participants or broadcast to an entire study. Study banners, colour-coded announcements displayed at the top of the participant dashboard, can be used for longer-running communications, with options for manual, date-based, or relative timing (e.g., "show 3 days after first login for 7 days").

Each research group operates in its own completely isolated environment within the platform. One group cannot see or access another group's studies, participants, or data. This isolation is enforced at the database level, not just in the user interface, so there is no technical pathway for data to cross between institutions. A researcher at one university cannot access data from another, even if both are using CircadiaLog.

Researchers create participant accounts individually or in bulk via CSV import. Accounts can be activated, deactivated (preserving all data), or permanently deleted (with anonymisation). Participants can be assigned to study arms and moved between study stages. Password resets are handled by staff; participants do not need email access.

There is no hard system limit on participant numbers. Participant quotas are configurable per research centre. Researchers can import up to 500 participants at a time via CSV upload, making large-scale studies straightforward to set up.

There is no hard system limit on the number of concurrent studies a research group can run.

Not within the same research group. Each participant account is scoped to a single study. If a participant needs to take part in two concurrent studies, they would require two separate accounts. This is a deliberate design decision to maintain clear data boundaries between studies.

Yes. The platform is fully timezone-aware. Each participant's timezone is automatically detected on first login, and all notifications, EMA schedules, and time calculations respect the participant's local time. Researchers view data with timezone context, and all times are stored with UTC offsets for accurate cross-timezone analysis.