Laughter fits from 25I-NBOMe

Laughter fits are a cognitive and physical effect characterized by episodes of spontaneous, intense, and uncontrollable laughter that occur without any identifiable humorous trigger or even a subjective feeling of finding something funny. Unlike the laughter that accompanies a genuinely increased sense of humor, laughter fits are notable for their involuntary and almost reflexive quality — the physical act of laughing begins and sustains itself independently of any corresponding feeling of amusement, as though the motor program for laughter has been activated directly without passing through the cognitive appraisal of humor. The fits can persist for seconds to many minutes and may be difficult or impossible to suppress through deliberate effort.

The physical experience of laughter fits can be remarkably intense. The laughter typically involves rhythmical, audible contractions of the diaphragm and respiratory muscles that may escalate from chuckling to full-body, convulsive laughter. At higher intensities, the fits can produce tears streaming down the face, aching abdominal muscles, difficulty catching one's breath, and an inability to speak or keep one's eyes open. The physical sensation is often described as a wave of energy moving through the torso that produces an irresistible urge to vocalize. Despite the absence of a clear humorous stimulus, many users report that the fits feel overwhelmingly positive and pleasurable, producing a cathartic release of physical and emotional tension.

Laughter fits are most commonly induced under the influence of nitrous oxide, where they are among the most characteristic and immediately recognizable effects — the substance's colloquial name "laughing gas" derives directly from this property. They are also frequently produced by cannabis, psychedelic compounds such as LSD and psilocybin, and certain dissociatives. The effect tends to be most pronounced during the onset or come-up phase of the experience and may occur intermittently throughout. Certain combinations of substances, such as cannabis with psychedelics, can produce particularly intense and prolonged episodes. The effect is more common in social settings, where the laughter of one person can trigger contagious fits in others.

In group settings, laughter fits take on a uniquely self-reinforcing dynamic. When one person in a group begins laughing uncontrollably, the sheer absurdity of witnessing someone laughing hysterically for no apparent reason can trigger laughter in others, creating a feedback loop in which each person's laughter fuels everyone else's. These cascading laughter fits are among the most commonly reported and fondly remembered aspects of social psychoactive substance use. The loops can persist for remarkable durations, sometimes exceeding 20 to 30 minutes, with each participant's attempts to regain composure being continually undermined by the ongoing hilarity of the situation.

While laughter fits are generally experienced as positive and enjoyable, they can occasionally become uncomfortable or problematic. Extremely prolonged or intense fits can cause significant muscle soreness in the abdomen, jaw, and face, and the difficulty breathing that accompanies intense laughter can produce moments of mild panic. In rare cases, the involuntary nature of the laughter can feel alarming if the person is unable to stop despite wanting to, particularly in inappropriate social situations. Some users report that the fits can briefly transition from pleasant to exhausting or even mildly distressing if they persist well beyond the point of enjoyment, though this is uncommon.

Laughter fits are closely related to but distinct from increased sense of humor. While increased sense of humor involves genuinely finding more things funny, laughter fits represent the physical act of uncontrollable laughter that may or may not be accompanied by a corresponding sense of amusement. The two effects frequently co-occur and amplify each other, but they can also manifest independently — one can experience intense laughter fits without finding anything particularly funny, and one can have a greatly enhanced sense of humor without necessarily erupting into uncontrollable laughter.