Use notifications API options (:all and :since)

> **all**
> *Optional* **boolean** `true` to show notifications marked as read.
>
> **participating**
> *Optional* **boolean** `true` to show only notifications in which the user is directly participating or mentioned.
>
> **since**
> *Optional* **time** filters out any notifications updated before the given time. The time should be passed in as UTC in the ISO 8601 format: `YYYY-MM-DDTHH:MM:SSZ`. Example: “2012-10-09T23:39:01Z”.

cite: http://developer.github.com/v3/activity/notifications/#list-your-notifications