A leaky air mattress becomes less comfortable as it loses firmness, and it can leave you lying on the floor by the morning. You can repair your mattress instead of buying a new one, however, even if you don't have a repair kit with patches.
Locating the Leak
Fill your mattress with air to its full capacity, then seal it like you would if you were setting it up for sleep. Take the mattress outside to an area that won't damage it further and lay it on the ground.
Fill a bucket with water and add some dish soap until it starts to make suds. Use a sponge to wipe the soapy water over the mattress. Look for an area that appears to be blowing out suds. This is your leak.
Mark where you found the leak, then wipe the mattress with a towel. Allow the mattress to fully dry in the air.
Fixing the Leak
Put on rubber gloves to protect your skin from the vinyl adhesive. Apply it to the hole or tear.
Allow the coat of vinyl adhesive to dry completely, then apply another layer. Keep applying layers until the coat is firm, or about 1/16 of an inch thick.
Allow the mattress to dry for at least 48 hours before using it.