With an inflatable car bed for the back seat, a little air leak is normal in even the best air beds. However, if you find that your air beds significantly deflate in the night, you will be forced to inspect it further. The inspection will enable you to discover any holes or ripped seams. In some cases, the culprit is a loose cap on your air valve. If that's the case, fill your air bed back up and make sure that the lid is securely fastened before you use it again.