In everyday speech, affect is a verb. It means to influence something, such as in the headline from the Albuquerque News, Downed Power Line Affects PNM Customers The downed power line had an impact on some power customers: they were without electricity overnight. Effect is most commonly used as a noun meaning the result or impact of something, an outcome. If there's "a/an/the" in front of it, it's an effect. The second sentence is from a story about the outcome of long-term sleeping trouble, The Effect of Persistent Sleepiness [Source.](https://www.vocabulary.com/articles/chooseyourwords/affect-effect/)