Risks of heart attack greater for people who wake early, says study
The University College London study found an “association” between the time they woke and mortality from cardiovascular disease.
In white Europeans there was a moderately increased risk from waking early but this was “not as strong” in other racial groups.
The study looked at more than 4,000 adults in Brent and Southall. It is believed to be the first to find evidence of differences in cardiovascular death rates linked to sleep between people of white European, South Asian and African-Caribbean heritage.
Dr Victoria Garfield, of the UCL Institute of Cardiovascular Science, said: “Even when taking into account a number of other risk factors, white Europeans who reported waking up too early were 1.3 times more likely to die from cardiovascular-related causes when compared to people of African-Caribbean or South Asian descent.
“We do not know the exact underlying mechanisms for why waking up early is associated with increased risk of CVD mortality. Thus, we need more research to investigate how other factors such as stress and working patterns may influence this relationship.”
It has been known for decades that people who sleep either for longer or shorter than normal have an increased mortality risk. Sleep duration and quality is thought to be affected by longer working hours, shift work and the move towards a 24/7 economy. These may contribute towards shorter sleep and increased daytime fatigue. The National Sleep Foundation recommends seven to eight hours of sleep a night for adults.
The UCL study looked at sleep quality and asked participants to recall whether they had difficulty falling asleep, had woken feeling tired or had woken early in the past 30 days.
It looked at the records of 4,399 people aged 40-69 who had been recruited for the Southall and Brent REvisited study between 1988 and 1991. Of these, 1,656 had died by December 2017 — of which 372 Europeans, 308 South Asians and 89 African-Caribbeans had died from cardiovascular disease.
Europeans were not found to be at increased mortality risk linked with difficulties falling asleep or waking feeling tired. Difficulty falling asleep was associated with moderately increased risk of mortality in South Asians, but this reduced when risks from diabetes and high blood pressure were factored in.
Joint author Roshni Joshi said: “Our study finds that being of South Asian descent and finding it difficult to fall asleep is linked to a higher rate of death, but we need more research, in bigger populations, before we can conclude this with certainty.” The study, in the journal Sleep Medicine, also looked at cancer deaths but found a “weak” association with sleep quality. ES