Hi~
 

This is Teacher Rach~ Here are your corrections:

Today is Monday.

As it says "Monday blues".

==> As they say, "Monday blues".

I get a little bit exhausted than other days.

==> I get a little bit more exhausted than other days.

Because drinking coffee in the late afternoon keep awake me all night.

==> Because drinking coffee in the late afternoon keeps me awake all night.

• vocabulary: 'as they say' is more commonly used if you're not quoting someone specific.
• comparatives: You should add 'more' before the adjective or '-er' at the end of an adjective if you're going to use 'than'. (ex: more beautiful than, prettier than)
• subject-verb agreement: Gerunds are always singular so you should use the singular form of a verb (ex: Dancing in the moonlight is...Eating breakfast is...)
• vocabulary: the pattern should be 'keep someone awake'
• I hope the suggestions will help! Keep posting~~