Smartphones Share User Data Overnight Despite Idle Status

Smartphones continue to send various types of data overnight, even when not actively in use, raising ongoing privacy considerations for users.

Overnight data transmissions from smartphones include system updates, diagnostics, and telemetry information. In addition to these functions, devices also send tracking-related data such as device identifiers, advertising IDs, and usage patterns that can be used for profiling and targeted advertising.

Academic research has found that some Android devices maintain communication with companies including Meta and Yandex, transmitting tracking data even after users attempt to restrict such activity. This ongoing data exchange can occur through multiple channels, including background services and network connections.

Phones may continue to share approximate location information via Wi-Fi, Bluetooth scanning, and connectivity metadata, even if GPS is disabled. These transmissions can occur without direct user interaction, contributing to the overall volume of data shared while the device appears idle.

What the numbers show

• Research identified ongoing data sharing with Meta and Yandex from Android devices
• NSA guidance includes regularly resetting advertising IDs and disabling ad tracking
• Multiple data types such as device IDs and location signals are sent overnight

Users seeking to reduce overnight data sharing can review and adjust app permissions, especially for location, microphone, camera, and tracking access. Restricting these permissions to only while using the app or never can help limit unnecessary data transmissions.

Additional steps include disabling Background App Refresh on iPhones or restricting background data and battery usage for individual apps on Android devices. Turning off personalized advertising features, such as disabling “Allow Apps to Request to Track” on iPhone or opting out of ad personalization and resetting the advertising ID on Android, can further reduce tracking activities at night.

Using a virtual private network (VPN) can obscure a device’s IP address and reduce network-based tracking, providing an additional layer of privacy while the phone is idle. Placing the device in airplane mode or powering it off overnight effectively halts all wireless data transmissions, though alarms can still function in these states.

The National Security Agency has recommended minimizing app permissions, disabling ad tracking, and regularly resetting advertising IDs as measures to protect user privacy. These steps are intended to help users manage the amount of data their devices share, particularly during periods when the phone is not in active use.

* This article is based on publicly available information at the time of writing.