The laughing gas that makes you giddy and alters your state of consciousness to a dreamy, floating-like state is anything but a laughing matter. The sweet-smelling gas, also known as nitrous oxide, has several side effects that alter brain activity. According to a recent study published in the journal Clinical Neurophysiology, brainwaves begin to alter to large-amplitude slow-delta waves for three minutes across the front of the brain once every 10 seconds after laughing gas is administered.

"We literally watched it and marveled, because it was totally unexpected,” said Emery Brown, author of the study, an Edward Hood Taplin Professor of Medical Engineering at MIT, and an anesthesiologist at Massachusetts General Hospital (MGH), in the news release. “Nitrous oxide has control over the brain in ways no other drug does.”

Nitrous oxide has been used in anesthesiology practice since the 1800s, but the way it works to create altered states is still not well understood. Generally, when doctors explain anesthesia to family patients, it is described as putting a patient to sleep, but this is inaccurate. Unlike sleeping, people who are drug-induced cannot remember, feel pain, or move, despite being physiologically stable. This state of coma persists as long as the flow of the drugs remains strong, and afterward, patients wake from anesthesia with the sensation that no time has passed.

Brown and his colleagues began to analyze brain activity after laughing gas administration in 2012. Brown began to record electroencephalogram (EEG) readings — depiction of electrical activity occurring at the surface of the brain — from all of his anesthesiology patients. During this process, a sticker with six electrodes is placed on the forehead of the patient to measure voltage fluctuations that come from the collective effect of neuron communication with the brain. The EEG signal transfers this into a computer that records it and shows the data as waves on a monitor in the operating room.

After the feedback of EEG monitoring, Brown and his colleagues found high-dose administration of laughing gas is associated with large-amplitude slow-delta brainwaves. The change in brainwaves occurred for a duration of three minutes after laughing gas was given to the patient. The researchers believe these waves form because laughing gas blocks signals from the brainstem that would otherwise maintain wakefulness.

Normally, when certain receptors in the thalamus and cortex are not bound by nitrous oxide, they receive excitatory signals from arousal centers lower in the brain. However, without these signals, a loss of consciousness occurs, which is marked by the production of slow waves. According to Brown: “If you see slow EEG oscillations, think of something having happened to the brainstem.”

Laughing gas is deemed medically safe to use, but recreational use and abuse of the gas can cause it to dissolve in the bloodstream and reduce the amount of oxygen flowing to the brain. The lack of oxygen being inhaled at the same time can lead to asphyxiation or loss of consciousness and even subsequent brain and organ damage, including oxygen deficiency, according to an article published in the journal Anesthesia Progress. Regularly using significant quantities of laughing gas can lead to a variety of medical problems, such as permanent nerve damage.

Apoptosis and myeloneuropathy are among some of the problems that can occur with high levels of laughing gas. In apoptosis, brain cells die in regions of the brain responsible for learning and memory. Infants and the elderly are among those at high risk exposed to it. In myeloneuropathy, myelin, the material covering neurons in the brain, is damaged and can slow down or stop brain functions, since laughing gas affects the body’s ability to use vitamin B12, which is essential for myelin.

Recently, laughing gas has resurfaced by becoming a popular option in the U.S. for women giving birth. In 2011, the Food and Drug Administration approved new nitrous oxide equipment for delivery room use. This ends up being a cost-effective option where women can opt for paying less than $100 for laughing gas compared to an epidural that can run up to $3,000.

The MIT study encourages anesthesiologists to use an EEG to monitor the brain states of their patients under anesthesia to make better anesthetic dosing decisions and alleviate concerns about awareness under anesthesia, especially for pregnant women.

The MIT researchers believe if anesthesiologists can find a way to make the large-amplitude slow-delta waves last longer than three minutes, it could become a potent anesthetic where rapid recovery would be possible in several medical procedures.

Source: Oluwaseun A, Brown EN, Ling K et al. Nitrous oxide-induced slow and delta oscillations. Clinical Neurophysiology. 2015.