People aged 18 and under should have a nightly curfew at 10 p.m. because they need more sleep than adults and the majority of violent crimes against youth occur after 10 p.m.

What do you expect to read in an essay with this thesis statement?
research proving why most people need more sleep
evidence that a majority of violent crimes are committed by youth
a section on sleep and a section on violent crimes
a proposal for schools to start class later in the day

In essays, a thesis statement does not only tell the reader the topic and claim of the essay but also suggest the content of it. In this way, most thesis statements include the position of the author and the reason or factors that support that position and these are also the main points that would be explained during the text.

This implies, if the thesis statement is "People aged 18 and under should have a nightly curfew at 10 p.m. because they need more sleep than adults and the majority of violent crimes against youth occur after 10 p.m." the two main reasons the author will use are " they need more sleep than adults" and "the majority of violent crimes against youth occur after 10 p.m." and therefore, the essay should present first a paragraph or paragraphs that explain and prove young people needs more sleep time and then a paragraph or paragraph that explains why crimes against youth occur after 10 p.m. Therefore, with this thesis statement you can expect to read a section on sleep and a section on violent crimes.