In some implementations, a computing device can confirm a sleep determination for a user based on secondary indicia of user activity. For example, the computing device can be a user's primary computing device. The primary device can predict and/or determine when the user is sleeping based on the user's use (e.g., primary indicia), or lack of use, of the primary device. After the primary device determines that the user is sleeping, the primary device can confirm that the user is asleep based on secondary indicia of user activity. In some implementations, the secondary indicia can include user activity reported to the primary computing device by other secondary computing devices (e.g., a second user device, a household appliance, etc.). In some implementations, the secondary indicia can include user activity detected by sensors of the primary computing device (e.g., sound, light, movement, etc.).