Aqualude, also known as quaalude, is a brand name for the sedative and hypnotic medication methaqualone. Originally developed in the 1960s as a treatment for insomnia and anxiety, it gained popularity as a recreational drug in the 1970s due to its euphoric effects. However, concerns about its potential for abuse and addiction led to its classification as a Schedule I controlled substance in the United States, effectively making it illegal. Today, it is rarely prescribed and is mostly associated with historical drug culture.