Effective date: 4 April 2026 · Helvellyn Ventures Ltd · Zeitgeber (iOS)
Zeitgeber is a sleep-optimisation tool for shift workers, not a medical device. Subscriptions auto-renew and are managed through Apple. You can cancel any time. These terms are governed by English law.
By downloading, installing, or using the Zeitgeber app ("the App"), you agree to be bound by these Terms of Service ("Terms"). Please read them carefully before using the App.
If you do not agree to these Terms, do not use the App. These Terms form a legally binding agreement between you and Helvellyn Ventures Ltd, a company registered in England and Wales ("we", "us", "our").
These Terms should be read alongside our Privacy Policy, which explains how your data is handled.
Zeitgeber is an iOS application designed to help shift workers manage their sleep and circadian rhythms. Based on the shift schedule, chronotype, and preferences you enter, the App generates personalised guidance on:
All recommendations are generated locally on your device. The App does not require an internet connection, a user account, or any personal registration.
We reserve the right to update, modify, or discontinue features of the App at any time, with or without notice. We will endeavour to notify you of material changes through an in-app notice or an app update.
Zeitgeber is a general wellness application. It is not a medical device, does not provide medical advice or diagnosis, and is not a substitute for professional medical care.
The recommendations provided by the App are based on general circadian science and are intended to support healthy sleep habits. They are not tailored to your individual health conditions, medications, or medical history.
If you have a sleep disorder, a chronic health condition, or any other medical concern, please consult a qualified healthcare professional before changing your sleep habits.
Zeitgeber has not been assessed, approved, or registered as a medical device by the Medicines and Healthcare products Regulatory Agency (MHRA) or any other regulatory body.
You must be at least 16 years of age to use Zeitgeber. By using the App, you confirm that you meet this requirement.
You must also have a valid Apple ID and access to the App Store to download and use the App.
New users receive a 28-day free trial upon first installing the App. During the trial, you have full access to all features of Zeitgeber at no cost.
After the free trial, continued access to Zeitgeber's full features requires a paid subscription. We currently offer two plans:
Billed monthly. Cancel any time.
Billed annually. Best value.
Prices are displayed in pounds sterling (GBP) and include any applicable VAT. Prices may vary in other regions based on local currency and App Store pricing.
Billing is handled entirely by Apple. We do not collect or store your payment information. All billing, receipts, and payment disputes are managed through Apple's App Store. By subscribing, you agree to Apple's payment terms.
Auto-renewal: Subscriptions automatically renew at the end of each billing period unless cancelled at least 24 hours before the renewal date. Apple will charge your Apple ID account on the day of renewal.
Price changes: If we change subscription prices, Apple will notify you before your next renewal. You may cancel before the new price takes effect.
Refunds: All refund requests are handled by Apple in accordance with their refund policy. We are unable to process refunds directly. To request a refund, visit reportaproblem.apple.com.
You may cancel your subscription at any time through your device's Apple ID subscription settings:
Cancellation takes effect at the end of the current billing period. You will retain access to paid features until that date. No partial refunds are given for unused time within a billing period, except as required by law.
After cancellation, you may continue to use the App in a limited capacity (the "You" tab remains accessible) or upgrade again at any time.
All content within Zeitgeber - including but not limited to the circadian algorithm, educational content, recommendation logic, design, text, graphics, and software - is owned by or licensed to Helvellyn Ventures Ltd and is protected by copyright, trade secret, and other intellectual property laws.
We grant you a limited, non-exclusive, non-transferable, revocable licence to use the App for your personal, non-commercial purposes in accordance with these Terms.
You may not:
You agree to use Zeitgeber only for its intended purpose. You must not:
To the fullest extent permitted by applicable law:
Nothing in these Terms affects your statutory rights as a consumer under UK consumer protection law, including the Consumer Rights Act 2015.
The App may contain references to scientific research, citations, or links to external websites. These are provided for informational purposes only. We are not responsible for the content, accuracy, or practices of any third-party websites or resources.
Your use of the App Store and Apple's billing services is subject to Apple's own terms and conditions, which are separate from these Terms.
You may stop using Zeitgeber at any time by deleting the App from your device and cancelling any active subscription.
We reserve the right to suspend or terminate access to the App if we reasonably believe you have breached these Terms or used the App in a fraudulent or abusive manner. In such cases, we will not provide a refund for any unused subscription period, except as required by law.
Upon termination, all licences granted under these Terms cease immediately. Provisions that by their nature should survive termination (including intellectual property, limitation of liability, and governing law) will continue to apply.
We may update these Terms from time to time. When we make material changes, we will notify you via an in-app notice before the changes take effect. The updated Terms will be published at zeitgeber.app/terms with a new effective date.
If you continue to use Zeitgeber after updated Terms take effect, you are agreeing to the revised Terms. If you do not agree to the revised Terms, you should stop using the App and cancel your subscription.
These Terms are governed by and construed in accordance with the laws of England and Wales. Any disputes arising from or relating to these Terms or your use of Zeitgeber shall be subject to the exclusive jurisdiction of the courts of England and Wales.
If you are a consumer resident in another part of the United Kingdom, you may also have the right to bring proceedings in your local courts under applicable consumer protection law.
We encourage you to contact us in the first instance to resolve any issue before pursuing formal proceedings. We aim to resolve all disputes fairly and promptly.
If any provision of these Terms is found to be invalid or unenforceable, that provision will be modified to the minimum extent necessary to make it enforceable, or severed if it cannot be modified. The remaining provisions will continue in full force.
These Terms, together with our Privacy Policy, constitute the entire agreement between you and Helvellyn Ventures Ltd regarding your use of Zeitgeber. They supersede all prior agreements or understandings.
If you have any questions about these Terms, or if you would like to raise a concern, please contact us:
We aim to respond to all enquiries within 5 working days.