ABSTRACT
External zeitgebers synchronize the human circadian rhythm of sleep and wakefulness. Humans adapt their chronotype to the day-night cycle, the strongest external zeitgeber. The human circadian rhythm shifts to evening-type orientation when daylight is prolonged into the evening and night hours by artificial light sources. Data from a survey of 1507 German adolescents covering questions about chronotype and electronic screen media use combined with nocturnal satellite image data suggest a relationship between chronotype and artificial nocturnal light. Adolescents living in brightly illuminated urban districts had a stronger evening-type orientation than adolescents living in darker and more rural municipalities. This result persisted when controlling for time use of electronic screen media, intake of stimulants, type of school, age, puberty status, time of sunrise, sex, and population density. Time spent on electronic screen media use-a source of indoor light at night-is also correlated with eveningness, as well as intake of stimulants, age, and puberty status, and, to a lesser degree, type of school and time of sunrise. Adequate urban development design and parents limiting adolescents' electronic screen media use in the evening could help to adjust adolescents' zeitgeber to early school schedules when they provide appropriate lighting conditions for daytime and for nighttime.
Subject(s)
Adolescent Behavior , Circadian Rhythm , Light , Photic Stimulation , Photoperiod , Sleep , Wakefulness , Adolescent , Adolescent Behavior/drug effects , Biological Clocks , Central Nervous System Stimulants/administration & dosage , Circadian Rhythm/drug effects , Computers , Cross-Sectional Studies , Female , Germany , Humans , Lighting , Male , Sleep/drug effects , Surveys and Questionnaires , Television , Time Factors , Video Games , Wakefulness/drug effectsABSTRACT
This study investigated the safety and feasibility of transvenous biventricular defibrillation in ICD patients. Some patients may have high DFTs due to weak shock field intensity on the LV. Animal studies showed a LV shocking electrode dramatically lowered DFTs. This approach might benefit heart failure patients already receiving a LV lead or conventional ICD patients with high DFTs. A modified guidewire was used as a temporary left venous access defibrillation electrode (LVA lead). In 24 patients receiving an ICD, the LVA lead was advanced through a guide catheter in the coronary sinus (CS) and into a randomized LV vein (anterior or posterior) using a venogram for guidance. Paired DFT testing compared a standard right ventricular defibrillation system to a biventricular defibrillation system. There were no complications or adverse events. As randomized, LVA lead insertion success was 87% and 71% for anterior and posterior veins, respectively, and 100% after crossover. Total insertion process time included venogram time (32.5 +/- 26.9 minutes, range 5-115, mode 15 minutes) and LVA lead insertion time (15 +/- 14 minutes, range 1-51, mode 7 minutes). An apical LVA lead position was achieved in 11 (45%) of 24 patients and 7 (64 %) of these 11 displayed a DFT reduction; however, mean DFTs were not statistically different. Transvenous biventricular defibrillation is feasible and was safe under the conditions tested. Additional clinical studies are justified to determine if optimized LV lead designs, lead placement, and shock configurations can yield the same large DFT reductions as observed in animals.
