Effects of prolonged wakefulness: the role of PERIOD3 genotypes and personality traits.

The roles of personality traits, as assessed by Eysenck Personality Inventory, and of the clock gene PERIODS (PER3) were analysed on the subjective effects of prolonged wakefulness. A sample of 70 healthy participants (7 men, 63 women; M age = 24.2 yr., SD = 3.2) was studied during forced wakefulness between 7:30 p.m. and 9:30 a.m. According to Eysenck's arousal model, it was hypothesized that prolonged wakefulness might affect in a different way those classified as Introverted and Extraverted. During the forced wakefulness period, the Introverted group showed greater decrease in subjective measures of vigilance than did the Extraverted group, but no differences were observed between groups with high and low scores on Psychoticism and Neuroticism. Prolonged wakefulness had a negative effect on subjective sleepiness and mood in all three PER3 polymorphisms analysed.

Dopamine activation in Neuroticism as measured by spontaneous eye blink rate.

Personality dimensions have been associated with different psychobiological systems. However, no agreement exists in literature on a specific role of a single neurotransmitter for each of the dimensions investigated. We studied the relationship of Neuroticism, Extraversion and Psychoticism as assessed by Eysenck Personality Inventory (EPI) with spontaneous eye blink rate (BR), a non-invasive measure of central dopamine activity. A total of sixty-three healthy subjects (40 females, 23 males, mean age 24.2±3.9) were studied. Spontaneous blink rate and time of blink suppression were assessed by EOG measurement. Levels of Extraversion and Neuroticism were inversely correlated. In contrast with previous findings, a significant correlation between blink rate measures and Neuroticism was found. No significant correlation between blink measures and either Extraversion, or Psychoticism were found. The results appear consistent with a lower threshold for activation in neuroticism as suggested by Eysenck's original model.

Good and Bad Sleep in Childhood: A Questionnaire Survey amongst School Children in Southern Italy.

Despite its clinical importance, the issue of subjective sleep quality in children remains unexplored. Here we investigate, in school-aged children, the prevalence of bad sleep perception and its relationships with sleep habits and daytime functioning, to provide hints on its possible determinants. Subjective sleep perception, sleep habits, and daytime functioning were studied through a questionnaire survey in a sample of 482 children (6-12 yrs.). Being "bad sleeper" was reported by 6.9% of the sample. Compared to the "good sleepers", these subjects displayed shorter sleep duration on schooldays, longer sleep latencies, and a more pronounced evening preference, beyond more frequent insufficient sleep. Though no differences emerged in sleepiness, bad sleepers showed higher impairments in daytime functioning, indicated by more frequent depressed mood and impulsivity. These distinctive features might be very important to precociously detect those children who are possibly more vulnerable to sleep disturbances and whose sleep-wake rhythms evolution should be paid particular attention thereafter. "The good people sleep much better at night than the bad people.Of course, the bad people enjoy the waking hours much more"Woody Allen.

Diurnal variation of spontaneous eye blink rate in the elderly and its relationships with sleepiness and arousal.

Sleep-wake rhythms in the elderly are deeply modified compared to young subjects, irrespective of physical or mental illnesses. However, still controversial are the results about age-related circadian variations of sleepiness levels. The objective of this study is to investigate the profile of diurnal sleepiness in healthy elderly subjects through subjective scales and by measuring spontaneous eye-blink rate (BR). In fact, we have previously found that BR, a reliable and non-invasive peripheral measure of central dopamine activity, increases in the young at times when subjective sleepiness is increased. Twelve healthy elderly volunteers (F=9, M=3, age range 64-79) participated in the experiment. At four times during the day (10a.m., 1.30p.m., 5p.m., 8.30p.m.), Karolinska sleepiness scale and a visual analogue scale for mood were administered to the subjects and BR was measured through vertical EOG. Alpha EEG power was used as objective measure of sleepiness. Sleepiness significantly changes across the day; according to post hoc contrasts, this is due to more sleepiness at 5p.m. Future research should be aimed at clarifying whether this peak is related to phase-advanced core body temperature in elderly people. Differently from the young, no significant differences were found in BR across the day, suggesting that an age-related modification of dopaminergic arousal mechanisms counteracting the rising sleep drive should be further explored.

Increased spontaneous eye blink rate following prolonged wakefulness.

Sleep deprivation (SD) is a technique of sleep-wake manipulation which has been used to treat depression. Changes in neurotransmitter systems, that are also involved in the effects of the antidepressant drugs, have been suggested as the possible mechanisms of action of SD. However, the therapeutic effect of SD is acute and transient, while antidepressant effects of drug treatments are gradual and stable. SD might work throughout mechanisms that are different from those mediating drug's effects. In the present study we analyzed the role of dopamine activity in SD. Spontaneous eye blink rate provides a non invasive measure of central dopamine activity. We assessed eye blink rate across prolonged wakefulness (from 10:00 a.m. to 07:00 a.m.) in 25 young normal subjects. Eye blink rate increased at the end of the wakefulness period. Blink rates and sleepiness as assessed by Karolinska Sleepiness Scale correlated positively with time spent awake. We propose that increased blink rate might reflect a dopamine activation that counteracts sleep drive. Antidepressant effects of sleep deprivation might be related to activation of the physiological mechanisms which regulate wake maintenance.