Final answer:
Research supports the statement that there has been an increase in reported loneliness, sleep problems, and self-harm between 2014 and 2018, linked to social media use and stress.
Step-by-step explanation:
The question regarding a substantial increase in reported loneliness from 2014 to 2018, along with increases in sleep problems and self-harm, is backed up by academic research. Studies such as those by van der Schurr et al. (2018) and Hunt et al. (2018) have examined the relationships between social media use, stress, and sleep in adolescents, as well as the impact of limiting social media on feelings of loneliness and depression.
Furthermore, the broader context of mental health concerns, as illustrated by Chen's report on Americans seeking more mental health help during the pandemic, aligns with these findings. While the statement does not specify a direct causal link, it does highlight a significant correlation witnessed over time.