Tranquillizing agents, commonly known as sedatives, are substances that reduce anxiety, stress, and hyperactivity in patients. In contrast, their antonyms are known as stimulants, which have an opposite effect on the human body. Stimulants primarily work by increasing the amount of certain neurotransmitters in the brain, leading to an increase in activity levels and alertness. Some common examples of stimulants include caffeine, nicotine, and amphetamines. However, excessive use of stimulants can lead to adverse effects such as restlessness, anxiety, and insomnia. Therefore, it is important to use these substances in moderation and under the guidance of a healthcare professional.