Our ancestors typically rose with the sun and went to sleep when it set , but modern life and artificial lighting has pushed this routine out of sync . However , researchers have discovered a rural community in Brazil that still follows the natural sleep cycles of the past - despite having access to the same technology as its urban neighbours . And they now plan to study this group to learn more about how our move away from the natural rhythm could be damaging our health . Researchers have discovered a rural community in Brazil that follows the 'natural sleep cycles ' ( stock image ) of our ancestors who rose with the sun , and typically went to bed when it set . The experts now plan to study this group to learn more about how our move away from the natural rhythm could be damaging our health . The community was discovered in the small town of Baependi in south-eastern Brazil in the state of Minais Gerais . Researchers from the University of Surrey and the University of São Paulo studied the population and asked them questions about their sleep habits and patterns . 'In big cities , the availability of cheap electricity has brought us both artificial lighting and a multitude of other electronic devices that compete with us going to sleep at night , ' said lead author Dr Malcolm von Schantz from the University of Surrey . 'As a result , most of us go to bed much later than our ancestors did , and , many of us are sleeping less . 'Even though the people in Baependi have access to electricity and television , their daily rhythms are much closer to those of previous generations . 'Studying this population is like being able to look back at past generations through a pair of binoculars and provide an insight into the benefit this natural pattern may be having on their health . ' Historian Roger Ekirch of Virginia Tech recently revealed an 'overwhelming amount of historical evidence ' that suggested we used to sleep in stages . He found more than 500 references about ancestors sleeping in two shorter periods throughout the night . The total sleep would occur in a 12-hour period that began with up to four hours sleep , an 'awake period ' of four hours and then ended with a second four-hour sleep . These days it is widely accepted human sleep patterns are governed by the 'circadian rhythm ' . This is the 24-hour cycle of being awake and then , when it becomes dark , resting . 'However , built into this 24-hour pattern is a series of shorter cycles of about 90 minutes - called the `` ultradian rhythm '' , ' added Dr Nerina Ramlakhan , author of Tired But Wired : How To Overcome Your Sleep Problems . This explains smaller peaks and troughs of energy throughout the day . Dr Ramlakhan believes this ultradian rhythm is a throwback to our hunter-gatherer years . And while we tend to pay much more attention to the 24-hour cycle than the 90-minute one , Dr Ramlakhan believes the body works best when we move with these natural ultradian rhythms , building in pauses , stopping and resting , so continually renewing our energy . The community was discovered in Baependi ( marked ) in south-eastern Brazil . Residents were asked when they would prefer to wake up and go to bed , and the average answers from the town dwellers were 07.15am and 22.20pm . Whereas people in the countryside preferred to rise at 06.30am and go to bed at 21.20pm . In particular , the residents were asked when they would prefer to wake up and go to bed if they were completely free to plan their day . The average answers from town residents were 07.15 and 22.20 , whereas people in the surrounding countryside preferred to rise at 06.30am and go to bed at 21.20 . The researchers believe the difference is due to town residents following much less of a natural sleep/wake cycle because of the influence of artificial lighting . 'When we asked the same question in London , the average answers were 08.30am and 23.15pm , ' continued Dr von Schantz . The paper explained that people in Baependi maintain a stronger link with the so-called solar rhythm because they predominantly work outdoors . They therefore have similar patterns as pre-industrial ancestors . Town residents follow less of a natural sleep/wake cycle because of the influence of artificial lighting ( stock image ) The paper explained that the people of Baependi , especially those in the countryside , maintain a much stronger link with the so-called solar rhythm . This is because they predominantly work outdoors and therefore have similar patterns as our pre-industrial ancestors . Solar time uses the mid-points of the light and dark 'periods ' - notably midnight and noon - as timing references . In circadian rhythms , sunrise start this clock on its 24-hour run , but this continues regardless of a shift in when the sun sets meaning the mid-points vary . 'Midnight really represents the middle of the dark phase , and yet many of us in the industrialised world are not even in bed by then , ' continued Dr von Schantz . 'Our colleagues at the University of São Paulo have studied this population , so there is a lot of data emerging about the health outcomes of the same population . 'We are optimistic that this project will teach us to what extent cardiovascular health , obesity , diabetes , and mental health problems may be associated with our move away from the natural day/night cycle , and the associated sleep loss . '
Study has found a Brazilian community with ' pre - industrial ' sleeping habits . They prefer to rise at 6.30am and go to sleep , on average , at 21.20pm . This is despite having access to the same electricity as urban residents . Nearby urban residents prefer to rise 07.15am and go to bed at 22.20pm . researchers said this is because the rural group predominantly work outdoors . They therefore have similar ' natural ' cycles as our pre - industrial neighbours . The community was discovered in the small village of Baependi . Researchers now plan to study this group to learn more about how a move away from the natural rhythm could be improving our health .