Ask A Scientist General Science Archive

name         karen
status       educator
grade        other
location     UT

Question -   Why does laughing gas make you laugh?  Does it make
everyone laugh?  Why or why not?  What are the side effects?  How long
can you inhale it before side effects take over?
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According to E. Cameron and P. May (Chemistry, University of
Bristol, UK) "laughing gas" or nitrous oxide was discovered by Joseph
Priestly. It has long been used as an analgesic (pain reduction) that is
both safe and effective. N2O effects are fairly quick, while inhaled, and
subside rapidly once inhalation is discontinued. As with all anesthetics &
analgesics, not much is understood about how they work. So the answer to
your first three questions is; nobody knows. 

M. Loop
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"Laughing gas" is a bit mis-named. It is nitrous oxide (N2O) and is used as 
a mild anesthetic, especially in dentistry. It is always co-administered 
with oxygen because alone it can cause suffocation -- otherwise it is 
fairly non-toxic. It is fast acting (within seconds), and its effects 
disappear within a minute or so after administration is stopped. It doesn't 
really make one "laugh". What it does is to give a sense of intoxication. 
In fact, when initially administered, it produces a sensation of anxiety 
before the sedating effect takes hold.

Vince Calder 
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Nitrous oxide, N2O, is commonly called laughing gas.
It has nothing to do with humor, but it is an anesthetic, a gaseous drug which partly suppresses the nervous system.
With the nervous system working slower, thinking is reduced, and rational inhibitions are partly reduced.
That can easily result in laughing, if a person emotionally would like to be a little silly.
In addition there is probably some euphoric effect, and perhaps some novel feelings vaguely resembling dizziness.
That too might incline a person with reduced inhibitions to laugh.

It doesn't make everyone laugh.
It gets used as a surgical anesthetic sometimes, and the subjects are as likely to calmly say incoherent things as to laugh.
An anesthesiologist would know in detail the side effects and dangers and the duration of exposure which would produce them.
I realize that laughing gas has been sampled without significant ill effects.
Personally, I don't know the typical limits, though I'm sure there are some.
If you get someone else to tell you, bear in mind that there is a difference between a conservatively safe exposure for everyone
and a likely-to-produce-side-effects exposure for average persons.

There is a scientific generality here.
Nitrous Oxide is not unique, it's just one of a broad class of gasses which slow down nerve transmission.
These gasses tend to be non-polar molecules with relatively high solvent-parameters
I.E., high cohesiveness with other molecules, but still gasses.
Perhaps they have their neural effect by soaking into fatty parts of neurons,
clogging synapse receptors or blocking ion-exchange channels, I don't know.
Sniffing glue and solvents is this same kind of thing, though probably more dangerous.
Inert gasses Krypton and Xenon have some of this kind of anesthetic effect,
but they are rare, expensive, and not artificially createable the way we do N2O.
Ordinary Nitrogen gas (N2), at high enough pressure (say, scuba diving more than 200 feet down) has this effect.
In that setting it's called "nitrogen narcosis".
Nitrogen has much lower cohesiveness than N2O, but the increased pressure makes up for that, pushing more gas into the neural tissues.

Jim Swenson
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Laughing gas is actually called nitrous oxide. While some people might laugh 
while using it, it is actually used to partly sedate patients by doctors 
such as dentists. It causes more of a calm, relaxed feeling, and in a third 
of patients it will cause a numbness in the lips, cheeks, and gums. There 
are very few side effects because laughing gas is one of the safest gases 
used for medical procedures. If to much nitrous oxide is enhaled it could 
cause a patient to become nautious. By removing the gas and letting the 
patient breathe pure oxygen, the patient will become fully alert within a 
matter of minutes

Grace Fields
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