Spill-over effects

When I read comments like: "I want to sleep, but I have to sit in the ICT class. :( It makes me sad and depressed. I think it will affect my effort at the economics lesson today :(((" then it reminds me of negative externalities. I think about the feelings/behaviour of one person might have a negative impact on others.

Of course here I am discussing a 'rational' human being' so hopefully such a negative event will not happen...but it is as well to be aware.

There is also the spillover effect of being sad and depressed.

'Spillover effect'?

Secondary effect which follows from a primary effect, and may be far removed from the event that caused the primary effect.

Ah, yes.

But what has caused this depression?

is it getting up early?

Is it not having your favourite Maths teacher?

IIs it having to wait so long before Economics - which is of course the peak point of the day?

Or is it the negative chemical reaction of something consumed earlier?

Click here and I think we'll all know.....