The exception is phenobarbital (Luminal), which is still used as a sedative and as an anticonvulsant .
Because of these additive effects, these medications taken with other sedatives or alcohol (also a sedative hypnotic drug) may increase chances for accidental death.
In general, most of the medications that induce sedation may alter breathing and cardiac stability.
Benzodiazepines (common sedative medication) have a cumulative effect.
This means that if the patient has not had time to metabolize the previous dose and ingests more, then the sedative effect may increase.
Sedation is typically used for common diagnostic tests that require prolonged immobilization such as magnetic resonance imaging (MRI) and computed axial tomography (CAT) scanning.