Google Analytics allows you to automatically monitor your data according to set preferences via a feature called Intelligence Events. No user intervention is required to enable this feature.
Analytics Intelligence constantly monitors your website's traffic and if it detects any significant anomaly it adds an automatic alert in your Intelligence Events (e.g. if your bounce rate suddenly jumps up on one of your referrals, then Analytics Intelligence will create an alert). In order to check the default alerts simply click on the Home tab as shown in the following figure:
As you can see in the above screenshot, there are three reports available -- Daily, Weekly, Monthly. Also, there is an Overview report showing your main highlights.
In the Overview report, you get to look at all of the automatic alerts that have occured during your selected time period. In the screenshot below, you can see all of the alerts that occured in Novemeber and December, along with the importance level of each.