Does serotonin cause yawning?

[Alfa]

Some drugs cause yawning(XTC, DXM, etc), but what pharmacological pathway or effect is making this possible? Since serotonin is related to sleep, my first guess is this may be related. Does anyone know?

[jazzmetalguitar]

SWIM has also heard of it in SSRIs so it is highly likely that there is a serotonergic pathway for yawning. However, SWIM also did some research today with apomorphine, which was little to no affinity for serotonin receptors and acts only as a dopamine agonist, but it caused considerable yawning as well. Perhaps there are several mechanisms? SWIM will hunt...he always likes to hunt and research...

[JaWill88]

swim yawns like 500 times when hes dope sick

[Mint boi]

I don't think a definite cause for yawning has been found. But one of the theories is indeed that serotonin and also dopamine may have something to do it. Another is that yawns help regulate body temperature, which could be a factor with drugs such as mdma.

Originally Posted by jazzmetalguitar

Perhaps there are several mechanisms?

I'd say that this is almost certainly the case.

Afterthought: Empathy yawns anyone? Could contribute to the case with mdma!!

[jazzmetalguitar]

It seems SWIM might be able to find a little bit everyone blaming this or that. It seems to be an extremely complex neurochemical process for such a simple effect. So, the answer is, no one knows, so we should theorize and rant like civilized people.

Here are the varied sources SWIM found (3 of tons):

Purports agonism of 5HT1c (serotonin receptor) is a piece of the puzzle and caused yawning as well as erection and no other systems could be implicated due to inability to stop effects. Though curiously 5HT2 agonists stopped the erection/sexual effects:
http://www.baillement.com/melis-ragi...nin-5ht1c.html

Purports it is dopaminergic because a lot of dopamine agonists cause it. Though ensures other systems must be involved:
http://www.baillement.com/cooper-dourish.html

Purports GABA is involved by stimulating nicotinic and muscarinic receptors with physostigmiine and then shutting off with GABA antagonists, however, GABA is a system which is known for acting with other neurotransmission systems:
http://www.springerlink.com/content/y507845666707188/

Lots of info. No straight line.

[Paracelsus]

The most common non-drug causes for yawning are lack of oxygen or seeing/hearing someone else yawn.

jazzmetalguitar: 5HT1c and 5HT2 are not substances/forms of serotonin but different serotonin (5HT) receptors.

[jazzmetalguitar]

Originally Posted by Paracelsus

The most common non-drug causes for yawning are lack of oxygen or seeing/hearing someone else yawn.

Thank SWIY for the correction. That was a rushed, sleep-deprived post with more errors than were even pointed out. Haha.

SWIM finds the contagious yawn absolutely fascinating. They are many, some even stranger theories on this. Two are: the 'mirror-neuron system' and this contagious yawn to be a returned yawn of empathy. Strange stuff.

[Euthanatos93420]

Swim Dex-yawns at the tail end of dex and on redoses following the same point in time he would normally start dex-yawning from the first dose.

[Paracelsus]

Gutierrez-Alvarez AM. Do your patients suffer from excessive yawning? Acta Psychiatrica Scandinavica 2007 Jan;115(1):80-1.

OBJECTIVE: Yawning has been described in relation to drugs such as serotonin reuptake inhibitors,
levodopa, dopamine agonists, MAO B inhibitor, morphine, methadone, buprenorphine, dextromethorphan,
benzodiazepine, lidocaine, and flecaine. This is a report of two patients, on long-term escitalopram
therapy (more than 8 weeks) with stable dosing, who presented excessive yawning. Escitalopram is
widely used in major depressive disorder and generalized anxiety disorder. METHOD: A clinical
description of two cases. RESULTS: Two females (62 and 59 years old, respectively) developed
excessive daytime yawning. It was not associated with sedation or a feeling of needing sleep.
The dosage was reduced and yawning disappeared some hours later. The patients' depression did
not recur. CONCLUSION: Yawning has been described in relation to different selective serotonin
reuptake inhibitors and remitted following their discontinuation; it is interesting that the
reported yawning in these two cases disappeared with the reduction of dosage, rather than the
interruption of treatment.


Sommet et al. Drug-induced yawning: a review of the French pharmacovigilance database. Drug Safety 2007;30(4):327-31.

OBJECTIVE: To review the reports with 'yawning' as an adverse drug reaction (ADR) reported into the
French Pharmacovigilance Database. METHODS: All the observations with 'yawning' reported in the
French Pharmacovigilance Database until December 2004 were reviewed. We recorded drug(s) involved,
characteristics of patients (age, sex and underlying disease) and of ADR (seriousness, delay in
occurrence, evolution, imputability). RESULTS: Twenty-eight reports were recorded between 1985 and
December 2004. The sex ratio of the patients included in these reports was 1.5 and the mean age was
46.2 (2-78) years. Thirty-eight drugs were involved, mainly serotoninergic agents (serotonin reuptake
inhibitors [12]), dopaminergic agents (levodopa [3], dopamine agonists [3], monoamine oxidase B
inhibitor [1]), opioids (morphine [1], methadone [1], buprenorphine [1], dextromethorphan [1]),
benzodiazepines (4) and sodium channel inhibitors (lidocaine [2], flecainide [1]). Four ADRs were
rated 'serious' (leading to hospitalisation). Patient outcome was usually favourable after drug
withdrawal. CONCLUSION: Despite its necessary methodological drawbacks (mainly under-reporting),
this study reveals that several drugs may induce yawning in humans. Our work also indicates that
stimulation of central dopamine or serotonin receptors elicits yawning in humans. This study underlines
the role of several drugs in yawning and shows that this ADR is not systematically listed in the summary
product characteristic even when it can be explained by the pharmacodynamic properties of the drugs.