Feeling Blues

Usually, women feel blues
a) when their monthly 'sea of red' comes ...
b) when they dun feel good abt 'anything and everything'.
c) after child-birth, as they called it - post-natal etc
d) if their child do not do well for exams...
and for many other reasons, I suppose.
Today, I was on one-day leave, and yet I feel blue ... just a strange feeling.
Perhaps, I feel that I really need a good long rest/sleep.