What is a known hypnotic (anesthetic) with a very short duration and white color?

Propofol is recognized as a hypnotic agent with a very short duration of action, making it particularly useful in procedures that require rapid induction and recovery from anesthesia. It works by enhancing the effects of the neurotransmitter gamma-aminobutyric acid (GABA) at the GABA receptor, leading to sedation and hypnosis.

In terms of its physical characteristics, propofol is typically presented as a white, opaque emulsion, which distinguishes it from other anesthetic agents that may be clear or have different appearances. Its rapid onset and short duration of effects allow for quick recovery times, making it an ideal choice for outpatient procedures or short surgeries where fast and clear recovery from anesthesia is desirable.

In contrast, agents like dexmedetomidine are primarily sedatives and have a different pharmacological profile, while isoflurane and sevoflurane are inhalation anesthetics that have longer durations and are not characterized by the same quick recovery period as propofol. This specificity of propofol in terms of its duration and physical properties aligns with the question's criteria, confirming it as the correct choice.