Nathan Z. answered • 11/24/21
APA Specialist, Editor, Academic Writing Consultant, and Journalist
Yes, "and" must be preceded by a comma. In this sentence, you're using "and" as a coordinating conjunction to connect two independent clauses (separate sentences).
An independent clause, or a complete sentence, contains three essential elements: 1.) a subject, 2.) a verb, and 3.) a complete thought.
In your sentence, the clauses in the first and second half could stand alone as their own, complete sentences, which means they are independent clauses (they contain a subject, verb, and complete thought):
1.) My goal was to fix my sleep schedule by getting 7 hours of sleep each weeknight.
2.) I originally planned to do so by setting a fixed bedtime of 1 AM and planning to wake up by 8 AM each night, Sunday through Thursday.
If you combined these independent clauses without a period, you'd get a run-on sentence. To avoid a run-on sentence (or comma splice), you must connect these independent clauses by using an em dash, semicolon, or coordinating conjunction.
You used the coordinating conjunction "and" to combine your independent clauses into one sentence. You must always use a comma before a coordinating conjunction that's connecting two independent clauses.
An easy way to remember most of the coordinating conjunctions is with the acronym FAN BOYS:
For, And, Nor, But, Or, Yet and So.
If you see any of these conjunctions between two clauses that can stand alone as their own, separate sentences, always place a comma before the conjunction.
