Every single meditation expert I know has given a warning with it. For some people, even 5 minutes is harsh. I've been in groups where people just break down and cry at that point.
One meditation coach once told me a story of one of his clients who did a 20 minute guided session, and he went out of it with vomiting, diarrhea, and was really angry at the guy. But a few days later, he felt something clear up and asked for more sessions. He says it's normal, and with corporate counseling, he normally restricts them to 5 minutes, 10 minutes, 15, 20, 30 for a week each.
One meditation coach once told me a story of one of his clients who did a 20 minute guided session, and he went out of it with vomiting, diarrhea, and was really angry at the guy. But a few days later, he felt something clear up and asked for more sessions. He says it's normal, and with corporate counseling, he normally restricts them to 5 minutes, 10 minutes, 15, 20, 30 for a week each.