I'm S sleepy

It's two  o'clock   in   the afternoon in Vietnam.  Right now,I'm working at in   the office with air-condition and it's very hot O outsite because this year  the weather is hot all year.  I' a m procee ssing the documents regard related to sales profit. I dont know why I'm alwayssleepy al even thought I had   have one hour to break for lunch time. I did have many ways to control  against my sleepy iness or drowsiness as took I just only  put a coold water in the bottle and put on it in my eyes,  I will massage it around my eyes. However, when I return to my seat, the   I'm still  sleepy is   or it doesn't change -.-) What should I do to against overcome the sleepy iness? from 13:00pm one o'clock to 15:00pm three o'clock This time is in the afternoon  is the most boring or yawnful.