It's 3 a.m., and your cellphone starts making its instantly recognizable, impossible-to-ignore you-just-got-a-text sound.
Your heart starts pounding. Is a loved one hurt? Is there some crisis at work?
You reach for the nightstand, pick up the phone and read: "Your number was selected as our iPad winner of the day! Enter 'IPAD' here to redeem!"
As you probably know, you are not really a winner of the day, you are the victim of mobile phone spam, a modern, insidious annoyance growing at an unacceptable rate.
American cellphone owners received 4.5 billion spam texts last year, according to Ferris Research, a market research firm that tracks mobile spam. That's more than double the number of spam texts received in 2009.
If all these unwanted texts are driving you insane, you are not alone.
The Federal Communications Commission reports that unwanted telemarketing calls and texts were consistently in the top three consumer complaint categories in 2011.
Having your personal mobile space interrupted by a text you didn't want is always annoying, but some of these spam texts are downright dangerous.
If you want to claim that "free" iPad, or a $1,000 Walmart gift card, you'll often be asked to divulge personal information that the spammer may sell to marketers or, worst-case scenario, use to access your bank account.
And if you think replying "STOP" to the message will make it all go away, think again. Any reply to the message will confirm only that the spammer has hit on a working cellphone number, and he or she can sell the number to marketers.
Even if you choose to ignore the texts, they can still show up on your phone bill with charges as high as $9.99 per unwanted text.
Text spamming is illegal under the Telephone Consumer Protection Act. The Federal Trade Commission is fighting some of the most egregious text spammers in the courts, and the major mobile carriers are investing in spam-fighting technology.
In the meantime, you can take action.
First, make sure your mobile phone number is registered with the FTC's do-not-call list, at www.donotcall.gov. This makes it illegal for a telemarketer to call or text you, unless you have given them permission to call, or they are exempt from the rules.
If you are an AT&T, T-Mobile, Verizon, Sprint or Bell subscriber, you can report spam texts to your carrier by copying the original message and forwarding it to the number 7726 (SPAM), free of charge.
If you are supremely organized, you can even file a complaint directly to the FCC, but be forewarned that requires filling out a rather lengthy form. Not convenient if the text comes at 3 a.m.
Android users will find scores of mobile phone spam-blocking apps at the Google Play store.
Mr. Number is one of the most popular of these services. PrivacyStar is currently available for BlackBerry, and is working on a version for Windows phones.
Unfortunately these apps are not available for iPhone users. Apple does not allow developers to block calls or texts.
And finally, take a close look at your cellphone bill and make sure that you didn't incur any charges from unwanted third-party spam.
If you did, call your carrier immediately and they will remove the charge from the bill.