your body has a range of biological cycles that happen very predictably some cycles many times a day some once every 24 hours and some take weeks or even entire year to complete and then start again so just how does your body manage to alter how to keep track of all these cycles in this episode of Psych boost circadian ripples on the roll and divers pacemakers and executive sight Gators [Music] right first off let's define two words that sound complicated or really are firstly endogenous pacemakers well endo is Greek for inside and Janice means producing so an endogenous pacemakers something insiders that presense ability to keep to time and you can think of this as an internal body clock now all clark's drift out of time every once in a while and need to be reset that's where the exactly the site Gator comes in the XO inexactness means outside so an outside producing and xyq gaiba is German but timegiver an exaction inside GABA is an environmental cue from the outside world that keeps our internal body clock to time and another word for this process is entrainment in this video we need to consider both the endogenous pacemaker and any exertion of site capers in relation to the circadian rhythm circadian rhythm ok last bit of etymology for this video circadian rhythm circuit is Latin for a bowel and DM is Latin for day so it's Acadian rhythm is a biological rhythm that lasts around 24 hours and while the sleep/wake cycle is the most obvious among the others we also have a circadian rhythm for releasing hormones and varying our body temperature well let's focus on sleep-wake cycle every 24 hours we have a period of sleep and a period of wakefulness and you may argue well I get to bed when the clock shows it's late or when it's dark and I wake up when the alarm goes off or the Sun comes up well there certainly cues so exertion of Psych a pers well we can see in situations like jetlag the conflict between those exactly acai capers and the internal body clock I don't use pacemakers tell none so it's far past our bedtime and then we need to sleep on the outside world is still light and the time is mid-afternoon it may take a couple of days for the exhaustion of sight gamers to adjust or entrain our endogenous pacemaker the Dodgers pacemaker for the sleep/wake cycle is a super cosmic nucleus or SCN it's also known as a master clock this is found in the hypothalamus within the limbic system just next I'll point on the optic nerves with a cross called the optic chiasm yes yin is sensitive to the amount and type of light received from the eyes the Sen is connected to the pineal gland which is also in the limbic system this produces melatonin a hormone that produces a sleep response so like detected by the Sen suppresses a production of melatonin in the pineal gland making you feel less sleepy this would mean that the main exception in sight gave up to the sleep/wake cycle is the amount of light received in the eyes our research has suggested social cues like when we time our meals or exercise or when others go to bed or environmental poos like clocks also work as exogenous I capers research evidence research evidence for the existence of a freerunning circadian and donkeyness pacemaker for the sea wake cycle is provided by Seif pre-running by the way means the endogenous biological rhythm or maintain itself without and Trainmen without external cues Seif conducted a number of studies in which he stayed for extended periods in a cave he was completely isolated from natural light or clocks in 1972 he spent 179 days about six months in a cave in taxes without access to the regularly timed exogenous site gamers of the Sun or clocks ceased body clock extend beyond the normal 24-hour cycle to around 25 hours where he still maintained a regular sleep wake pattern showing the freerunning circadian exactness like gaber in action but due to the slightly extended cycle he reported feeling less time and passed and expected a criticism of this and other studies with similar methodologies I showed similar results it is that participants had control over the artificial lights some psychologists have suggested that the participants in these studies were altering their biological clock with their use of the artificial lights more recent work by Caesar who controlled this variable suggests there might be no drift and the endogenous pacemaker is precise capable of an almost perfect 24-hour rhythm evidence of light is a dominant exogenous I gave it is strong better in 2011 showed that when exposed to strong blue light 27 office workers in the experimental group which much sense occasion rhythms with the office lighting compared to a control group of 27 office workers with normal office lighting whose River matched the natural light of dawn more about evidence of the SCN is the biological structure is the endogenous pacemaker responsible for circadian rhythm in the sleep/wake cycle this is provided by Ralph he destroyed the SCN of hamsters for the Tal mutation this gives him a circadian rhythm of just 20 hours he replaced it with the Sen of normal hamsters after this procedure the mutant hamsters had a normal schedule rhythm of 24 hours this also working reverse normal hamsters given the axiom from mutant hamsters would gain a 20 hour sleep-wake cycle this clearly demonstrates the Sen is the endogenous pacemaker in the sleep/wake cycle evaluations as a disruption to sleep patterns can lead to increase anxiety and also to decrease the alertness and decrease vigilance understanding how the seaquake cycle is affected by exactness psyche gaber's can help psychologists develop treatments for jetlag to improve performance of athletes who travel and to help shift workers be more productive and alarm this means it's Erie psychology has potential implications to the wider economy and understanding of the circadian rhythms like the circadian blood pressure rhythm helps of timing drug treatments benefiting health services like the NHS knowing the psychological effects of exposure to light particularly blue line as implications as technology changes and were exposed to more blue light at night and from personal devices a new LED road lighting this provides people were advice and how to maintain a healthy sleep at it does seem that light is a menexenus I gave her and social cues are less effective at reset in the biological clock research on a man blind from birth by Miles showed that even with social cues the blind man had a twenty four point nine our circadian rhythm meaning his sleep was out of synchronization with the rest of society there is an evolution explanation for the day/night cycle of humans and other animals specialized for daytime activity because we're not specialized for nighttime activity it makes no sense for us to move around in the dark nocturnal animals howlite rats were active at night have a circadian pacemaker where it shifted 12 hours so their wakefulness is at 9:00 bonus fact this area of research is called chronobiology and the presence of biological rhythms is common with even creatures as small - cyanobacteria having a circadian rhythm but the circadian rhythm can be turned off if not needed some species like arctic reindeer lose a circadian rhythm in the Arctic summer on the Sun never sets and migrating birds can turn those off of weeks so they can go about sleep to reach their destination I hope you found the Cyprus video useful if you did have made more than 140 for the psychology videos to help you these studies as well as a website all three resources if you want help cyclists grow subscribe and like also tell you teacher and anyone else you know who study psychology about the channel thanks for watching keep setting