The KnowHOW team explains: Mass display of tiredness and boredom is often triggered by the first act of yawning by someone. Seminars and meetings often go through such stages.

Despite that scientists often dispute whether yawning is contagious or nor. The amazing sight of someone’s yawning inducing a cascading effect in others may statistically be compared to some other experiences, sometimes summed up as the Murphy’s Laws. Sayings like, “The other queue finishes first”, “Buses on the other way are always aplenty” and “It is sure to rain if you forget the umbrella” are results of events which are impressive enough to be stored in our long-term selective memory. Series yawning (?)is amazing enough to be preserved in our brain.

Another idea is that we yawn when we feel drowsy. If a group is closed for a long time in a stuffy room, as seminar or reporting rooms usually are, everyone in the group will need more oxygen and get it by yawning, which is actually a slow deep breath followed by an equally long expulsion of carbon dioxide. Someone’s yawn in that environment will signal to others’ subconscious that it has been a long time since they began. No wonder everybody will long for a rest then, probably expressing their desire through a long y-a-w-n.

The question was sent by Pranab Sarkar from Calcutta-91