1/3. Decreased human circadian pacemaker influence after 100 days in space: a case study.OBJECTIVE: The objectives of this study were (1) to assess the circadian rhythms and sleep of a healthy, 42-year-old male astronaut experiencing microgravity (weightlessness) for nearly 5 months while living aboard Space Station Mir as it orbited Earth and (2) to determine the effects of prolonged space flight on the endogenous circadian pacemaker, as indicated by oral temperature and subjective alertness rhythms, and their ramifications for sleep, alertness, and performance. methods: For three 12- to 14-day blocks of time (spread throughout the mission), oral temperatures were taken and subjective alertness was self-rated five times per day. sleep diaries and performance tests were also completed daily during each block. RESULTS: Examination of the subject's circadian alertness and oral temperature rhythms suggested that the endogenous circadian pacemaker seemed to function quite well up to 90 days in space. Thereafter (on days 110-122), the influence of the endogenous circadian pacemaker on oral temperature and subjective alertness circadian rhythms was considerably weakened, with consequent disruptions in sleep. CONCLUSIONS: Space missions lasting more than 3 months might result in diminished circadian pacemaker influence in astronauts, leading to eventual sleep problems.- - - - - - - - - - ranking = 1keywords = near (Clic here for more details about this article) |
2/3. Transient short free running circadian rhythm in a case of aneurysm near the suprachiasmatic nuclei.A free running circadian rest-activity cycle is rare in sighted individuals living in a normal environment. Even more rare is a periodicity shorter than 24 hours, as observed in actigraphic recordings in a female patient during convalescence after a whiplash injury in a car accident. The documented free running period was 22.5 hours for 19 days. During the subsequent weeks re-entrainment occurred following re-establishment by a social zeitgeber, with a slightly early circadian phase of nocturnal melatonin onset relative to a late sleep period. magnetic resonance imaging and cerebral angiography showed an aneurysm at the bifurcation of the right internal carotid artery, close to the circadian pacemaker structure (the suprachiasmatic nuclei), which was later occluded.- - - - - - - - - - ranking = 4keywords = near (Clic here for more details about this article) |
3/3. fatigue and related human factors in the near crash of a large military aircraft.INTRODUCTION: During approach to a remote island location, a U.S. Air Force heavy-airlift aircraft was flown into an aerodynamic stall, resulting in the loss of more than 4000 ft of altitude, with the crew recovering the aircraft just before impact would have occurred. methods: An analysis of the mishap was conducted through a review of non-privileged USAF mishap data, cockpit voice recordings, flight data records, and interviews of the aircrew involved. A thorough examination of fatigue-related factors was conducted, including computerized fatigue modeling. RESULTS: The crew traveled over 11,000 mi in a westward direction over a 6-d period. They had been on duty for nearly 21 h on the day of the mishap, with minimal in-flight rest. The pilots were late beginning their descent for landing, and a minor aircraft malfunction distracted the crew, contributing to channelized attention and degraded situational awareness. A breakdown in crew communication and failure to adequately monitor and interpret true aircraft state culminated in loss of aircraft control. Analysis of the crew's work/rest schedule confirmed that multiple elements of fatigue were present during this mishap, including acute and cumulative fatigue, circadian disruptions, and sleep inertia. Additionally, reduced situational awareness and spatial disorientation, exacerbated by the underlying fatigue, were causal in this mishap. DISCUSSION: This mishap highlights the importance of maintaining a high degree of situational awareness during long-haul flights with a continuing need to address issues regarding spatial disorientation, proper application of human engineering principles in modern cockpits, and mitigation of aircrew fatigue factors.- - - - - - - - - - ranking = 5keywords = near (Clic here for more details about this article) |