Meditation should be done sitting on the floor or on a chair. A lot of people in my meditation classes asked me if they can meditate lying down. The answer is no because you get too relaxed and there is a good chance that you might fall asleep. You want to be alert and awake when you meditate.
One thing nearly every different meditation discipline has in common is an emphasis on the use of proper posture. To experience meditation’s calming, stress-reducing benefits, it must be practiced properly, and correct posture is a vital first step. You should try to keep your spine straight when you meditate. This will allow the energy to easily flow upwards from the base of your spine.