out of body experience and nausea

hi everyone, occasionally i wake up in the middle of the night and start to experience an OBE. last night it happened again; i relaxed and tried to get out the window, but was unable to; i floated up a bit and then came back down. this usually happens in three's -- 3x each. sometimes it's a pleasant experience, but more often i feel nauseous and it's somewhat unpleasant. does anyone else have this experience? if so is there any way to prevent this from happening? also in order to get outside, i didn't open my eyes but just pictured going through the window, but that didn't work; any ideas? thx, saleena