Addiction: Central nervous system (CNS) stimulants are addictive, even if they are not abused. Many factors, including the patient's personal history, the type of stimulant that is being taken, the dose of the drug, and duration of use, influence how likely an individual is to become addicted.
The source of all waves - mechanical or electromagnetic - is something that is vibrating. Matthew Donovan.
In summary, there are many kinds of waves and to create a wave there must be an energy source. The waves then contain that energy and the energy can be extracted from the wave thereby diminishing the wave.