While there are steamers that shut off automatically if it gets overheated or if the water gets too low. It's still not advisable to leave it unattended when plugged in or not in use as it might get very hot so you take the risk of fire if left on overnight. You could also burn out the wiring.
Steamers come in many shapes and sizes, but their basic function remains the same – a wand that blows out hot steam. The heat and water vapor are most commonly used to smooth out wrinkles in clothing, but it can also be used on drapes, upholstery, wig styling, car interiors, and more.
Steamers are easy to use and following just a few tips will make you look like a professional. Check out some tips on how to select and get the best results from a clothes steamer at About.com.