Sleep isn't a masterpiece but it's a pretty good debut from Jason Yu with strong directing, interesting writing and great performances from the cast members. Yu's direction and writing does a pretty good job on balancing out the tones of comedy and horror and creating a good sense of tense and terrifying atmospheres surrounding the setting and characters. The main premise is definitely very interesting as I don't see many movies focus on horror elements regarding sleepwalking or so forth. The narrative, while does have some faults and could have explored certain aspects a little more, is solid with good dialogue and executions being satisfying.
All of the performances are really good as each of the cast members does a good job on performing their characters. The soundtrack, production sets and the dialogue is pretty good too. While some depth in the characters could have been explored a bit, I found the characters to be entertaining to observe. There are some moments that were well-executed, especially a scene regarding PowerPoint's that was really entertaining. On the structure, the movie is a slow-burn but not once the movie felt slow or dull.
Overall, I am impressed with Jason Yu's first feature. No doubt there are some flaws but Yu's talent is pretty impressive enough to not overshadow the entire movie. I look forward to see what Jason Yu can offer in the future with his talents.