Site Uptime is a website monitoring service that checks your website at regular intervals. The online service can notify you via email or SMS if it becomes unavailable at any time.
By using a service like this one you can take a safe sleep during the nights knowing that your website will be monitored. In case of any failure from any of the locations where the service has connection points, they will email you or send you an SMS to wake up and take further actions.
For example if you are a webmaster or web owner you can use this service to monitor your web properties.
Go to Site Up Time