A new study published in Frontiers of Psychiatry confirms older studies that say smartphone addiction can ruin your sleep.

The definition of smartphone addiction, according to those who consider themselves addicts, is “less interest in personal relationships, use in spite of knowledge of the negative consequences, impaired control and preoccupation with their devices, and fear when their phones are inaccessible.” These descriptors, according to the sleep and smartphone study researchers, “are not dissimilar to the symptom domains of substance use disorders or other behavioral addictions.”

The study asked 1,043 King’s College London students, ages 18 to 30, to fill out two online questionnaires in person that listed sleep quality and smartphone use. Based on the results of the questionnaire, the researchers found that nearly 40% of students qualified as smartphone addicts. While the study did not show a direct link, it found that those who used their smartphones the most reported poorer sleep quality.

Robert Calandra is an award-winning journalist and author who has written extensively on health and medicine. His work has been published in national and regional magazines and newspapers.