Is there any harm in sleeping with real plants in the room do they release any toxins or gases?

No.

This is extremely unlikely. I think this strange myth began because someone learned that plants respire at night--same as you--which consumes oxygen and releases carbon dioxide. So the worry is that maybe you and your plant are competing for oxygen.

Rather than immediately framing your house plant as an oxygen hog ask yourself whether sleeping in the same room as another person could endanger your health in the same way?

It would be interesting to calculate the total amount of oxygen that an average house plant consumes over an evening. My guess is it is equivalent to a few breaths taken by the average human being.

In fact, I encourage you to look into the benefits of having plants indoors

Go forth and google this!

With respect to other toxins, while there may be exceptions (because of the incredible diversity of plants out there), I would be very surprised if a houseplant released any toxins that could harm you.

http://www.blankees.com/house/plants/air_cleaners.htm

http://www.home-air-guide.com/living-air-purifier.html

http://www.hgtv.com/landscaping/houseplants-indoor-air-purifiers/index.html