Aim:The purpose of this study was to examine the association of Internet overuse with excessive daytime sleepiness (EDS).Methods: A total of 2336 high school students in South Korea (boys, 57.5%; girls, 42.5%) completed the structured questionnaire. The severity of Internet addiction was evaluated using Young's Internet addiction test. Results:The proportions of boys who were classified as Internet addicts and possible Internet addicts were 2.5% and 53.7%, respectively. For girls, the corresponding proportions were 1.9% and 38.9%, respectively. The prevalence of EDS was 11.2% (boys, 11.2%; girls, 11.1%). When Internet addicts were compared with non-addicts, they consisted of more boys, drank alcohol more, and considered their own health condition as poor. But smoking was not related with Internet addiction. The prevalence rate of EDS for Internet addicts was 37.7%, whereas that for possible Internet addicts and non-addicts was 13.9% and 7.4%, respectively. The prevalence of insomnia, witnessed snoring, apnea, teeth grinding, and nightmares was highest in Internet addicts, middle in possible addicts, and lowest in nonaddicts. With adjustment for duration of Internet use, duration of sleep time, age, gender, smoking, taking painkillers due to headache, insomnia symptoms, witnessed apnea, and nightmares, the odds of EDS were 5.2-fold greater (95% confidence interval [CI]: 2.7-10.2) in Internet addicts and 1.9-fold greater (95%CI: 1.4-2.6) in possible Internet addicts compared to non-addicts. Conclusion:Internet addiction is strongly associated with EDS in adolescents. Clinicians should consider examining Internet addiction in adolescent cases of EDS.

We demonstrated that phlorotannins promote NREMS by modulating the BZD site of the GABAA receptor. These results suggest that phlorotannins can be potentially used as an herbal medicine for insomnia and as a promising structure for developing novel sedative-hypnotics.

The purpose of this study was to investigate both the sleep environment and sleep quality in bedrooms. It was also to reveal the relationship between sleep environment and sleep quality, and to study its seasonal changes in winter, spring, and summer. The subjects for this study were 24 women who lived in apartments in Seoul and its environs. We conducted two groups of measurements. One group considered elements of the sleep environment: mean radiant temperature, air temperature, relative humidity, carbon dioxide (CO2) concentration, illumination, and equivalent noise level. The other looked at elements of sleep quality: the apnea— hypopnea index, and inspiratory flow limitation (as %FL), which were measured simultaneously while subjects were asleep. Results showed first, that people were exposed to a variety of problems when asleep, related to their sleep environment such as too low or high air temperatures, or relative humidity and high CO2 concentrations. Second, these were seasonally dependant and people slept best during spring, then winter, and then summer. Third, the effect of the sleep environment on sleep quality varied with age.

Our previous study demonstrated that phlorotannin supplement had a sleep-promoting effect in rodents. In the present study, we investigated whether the phlorotannin supplement could improve sleep in subjects with self-reported sleep disturbances. In a randomized, double-blind, placebo-controlled trial, 24 subjects consumed either a placebo or phlorotannin supplement (500 mg/day) for 1 week, 30-60 min prior to bedtime. Sleep parameters were assessed at baseline and at 1 week with sleep questionnaires and polysomnography. At the end of the treatment period, the complete sets of sleep parameters from 20 subjects. Phlorotannin resulted in a significant increase in "Sleep duration" scores compared to the placebo (p = .044), although there were no significant differences on the total PSQI scores. Polysomnography revealed that wakefulness after sleep onset was significantly lower in the phlorotannin group compared to the placebo group (phlorotannin vs. placebo, -25.5 ± 30.5 vs. -1.7 ± 14.9; p = .045) as well as total wake time (phlorotannin vs. placebo, -0.9 ± 3.0 vs. -6.1 ± 6.8; p = .048). Additionally, the respiratory disturbance index during supine rapid eye movement sleep was significantly lower in the phlorotannin group (p = .035). There were no serious adverse effects in either group. Our data suggest that the phlorotannin supplement improved sleep maintenance (WHO ICTRP: KCT0001892).

This study investigated the psychophysiological effects of sleep deprivation on auditory event-related potentials (AERPs) and their relationship with psychological parameters. Twenty-four subjects remained awake for 37 h under continuous surveillance. In the mornings and the evenings of 2 consecutive study days, AERPs were recorded and 4 self-rated scales (sleepiness, fatigue, anxiety, and mood) were quantified. The latencies of P300 and N200 were significantly prolonged (p < 0.001) and their amplitudes decreased (p < 0.05) as a consequence of sleep deprivation. However, the only significant change in N100 and P200 was an increase in the P200 amplitude (p < 0.05). The increase in the latencies of P300 and N200 were correlated with increased sleepiness (p < 0.05), and the increase in P200 amplitude was correlated with negative mood, anxiety, and fatigue (p < 0.05). Although the changes in P300 and N200 induced by sleep deprivation are due to sleepiness, which may slow cognitive processing and decrease the efficiency of mental processing, the increase in P200 may be related with increased anxiety, negative mood, and fatigue.