It is an amazing experience. I have been twice now and the second was even better than the first. It’s so peaceful and relaxing. This was to the point I fell asleep. That certainly doesn’t happen during the day usually for me. Everything is your choice. If you’re worried about feeling claustrophobic, don’t. It’s your choice whether lights are on or off and your choice whether you close the lid or have it wide open. Just do it, go for it.