If you sync your sleep data through an external device, such as Apple Health or Fitbit, the date shown is based on the midpoint of your sleep time. If the midpoint is after 6pm, the sleep metric will be added to the following day. If the midpoint is before 6pm, the metric will be added to the date when the sleep started.
We understand if this might be confusing. If you have questions or input, please reach out to support@vida.com and we’d be happy to help.