Cerebral blood flow in the prefrontal cortex while reading a novel on a tablet computer and its effect on sleep: Temporary and remaining changes

摘要

We aimed to investigate how reading a book on a tablet computer affects sleep by measuring cerebral blood flow in the prefrontal cortex. Seven students (7 men, age: 21-32 years) participated in this study. Under a controlled illuminance environment, the subjects read a novel in printed form or on a tablet computer from any distance. As the subjects were reading, the cerebral blood flow in their prefrontal cortex was measured using near infrared spectroscopy. The study protocol was as follows: subjects (1) mentally counted a sequence of numbers for 30 s as a pre-test to standardize their thinking, (2) read the novel for 10 min using a printed book or tablet computer as a task, and (3) mentally counted a sequence of numbers for 30 s as a posttest. Step (2) was performed in a random sequence. Subjects rested between the two tasks. The results showed significantly increased cerebral activity (increase in regional cerebral blood flow) both during and after reading a novel on a tablet computer compared with reading a printed book. Furthermore, the region around Broca's area was more active when reading on a tablet computer. Considering the results from this study and from previous studies on physiological characteristics during non-rapid eye movement sleep, we concluded that reading a book on a tablet computer before the onset of sleep leads to potential inhibition of comfortable sleep through mechanisms other than the suppression of melatonin secretion.