I would work my way up to all night. Sometimes if you are very raw inside you can't retain it all night at first until the inflammation calms down. Again, this can't be repeated enough-- make sure you squeeze all the air out of the bottle
or it will make you crampy and you can't hold it in. Unscrew the cap, push the liquid up to the top and screw it back on. Then squeeze just a smidgen out. Start out with a half hour, then 45minutes to an hour the next night and so on until you eventually work up to all night--just to see how you react to it. (They usually give you plenty of bottles). I personally cannot do all night. I get really horrible cramps in the morning when I do and I go to the bathroom too many times. But an hour or so at night works very well for me when I'm in a flare. I usually lie down on my side and apply it, and watch TV while I'm waiting. I have never had a leaking problem once it's all in, but do put something down like an old towel on the couch or bed because it might leak just a little when applying because it can stain. Don't be alarmed if your bowel movements are darker with a whiteish cast to it the next day.