These rhythms are entrained to the period of a 24 h day by environmental signals or “zeitgebers,” meaning time-givers (Aschoff et al., 1971).
In humans, circadian rhythms in physiological and psychological variables are endogenously generated by a central circadian pacemaker-located within the suprachiasmatic nucleus of the hypothalamus-with a period of approximately 24.2 h (Czeisler et al., 1999 Zhou et al., 2011b). Many physiological and psychological variables in humans have been shown to alter rhythmically with a ~24 h period, including core body temperature (Dijk et al., 1992 Zhou et al., 2011a, 2017) cortisol (Scheer et al., 2009), blood pressure (Scheer et al., 2010), heart rate (Scheer et al., 2010), hunger (Sargent et al., 2016), cognitive performance (Dijk et al., 1992 Darwent et al., 2010 Matthews et al., 2010), strength (Reilly et al., 1997 Sargent et al., 2010), balance (Sargent et al., 2012b), flexibility (Reilly et al., 1997), dexterity (Matthews et al., 2012a, b), subjective alertness (Dijk et al., 1992 Zhou et al., 2012 Kosmadopoulos et al., 2014), subjective fatigue (Ferguson et al., 2012), subjective sleepiness (Kosmadopoulos et al., 2017), and objective sleepiness (Lavie, 1986 Dijk and Czeisler, 1995 Paech et al., 2010, 2012 Sargent et al., 2012a). The term “circadian rhythms” refers to rhythms with a period of approximately 24 h (Halberg, 1959). Jet Lag is Caused by the Desynchrony Between the Circadian System and Local Time Cues These guides could be applied by athletes competing in the Tokyo 2020 Olympic Games, but they could also be applied by athletes traveling to other countries for training or competition, or by non-athletes traveling for business or pleasure.
Eastward physical copy how to#
The purpose of this manuscript is to discuss the causes and consequences of jet lag and to provide examples of how to use judiciously timed light exposure/avoidance and/or exogenous melatonin ingestion to adapt the circadian system to a new time zone after transmeridian flight.
In either case, athletes will want to adjust to the new time zone as quickly as possible so that they can prepare well and/or compete at the highest level. Some athletes will travel to Japan, or nearby countries, weeks before their events, while others will arrive in Japan in the days prior to competition. For example, athletes traveling to Japan from North America and Western Europe will face time zone changes of 8–11 h west and 6–8 h east, respectively. Athletes will travel from all over the world to compete in the Games, and many will have to travel across several time zones. In August 2020, the Olympic Games will be held in Tokyo, Japan. These symptoms include headache, irritability, daytime sleepiness, difficulty sleeping at night, poor mental and physical performance, and poor gastrointestinal function (Waterhouse et al., 2004)-primarily caused by the mismatch between the circadian system, or internal body clock, which is synchronized to time cues in the departure time zone, and the desired timing of sleep and wake, which are typically synchronized to time cues in the destination time zone.
In contrast, jet lag refers to a collection of symptoms that occur in the days after flight across three or more time zones. These symptoms include fatigue, disorientation, and headache (Waterhouse et al., 2004)-primarily caused by the sleep loss, dehydration, hypoxia, and discomfort associated with being in an aircraft with confined space, recline-restricted seats, low air pressure, low humidity, etc., for 8–14 h (Brown et al., 2001 Roach et al., 2018). Travel fatigue refers to a collection of symptoms that occur during or immediately after long flights. Anecdotally, these effects are often referred to collectively as jet lag, but they are actually two separate phenomena-travel fatigue and jet lag-each with their own causes and consequences (Waterhouse et al., 2004).
Air travel across several time zones, i.e., transmeridian flight, causes negative effects-some of which occur during flight and some of which occur in the days after flight.
0 kommentar(er)
