There's a new calculator on the internet that tells you the optimal times you should go to sleep, based on what time you want to wake up.

The Sleep Calculator will take your desired wake up time, and give you several choices on when it's best to go to sleep.

According to the Sleep Calculator website, sponsored by a measure-to-order online blinds company, it's important that your sleep is done in full sleep cycles. It says that waking up in the middle of a sleep cycle "can leave you feeling grumpy and tired; rising in between phases will help you to start the day with a smile on your face."

You'll find the calculator here.