Research into longevity invariably lands on the importance of eating well and engaging in regular exercise. Less resources have been devoted to assessing the impact your mental health can have on your overall life expectancy. That is not to say studies haven’t been conducted in this area. In an influential Canadian study, depression was associated with an increased risk of premature death.
To further test this hypothesis, and determine the optimal time for rising, lead author Iyas Daghlas, M.D., turned to data from the DNA testing company 23 and Me and the biomedical database UK Biobank.
Daghlas then used a method called “Mendelian randomization” that leverages genetic associations to help decipher cause and effect.
“Our genetics are set at birth so some of the biases that affect other kinds of epidemiological research tend not to affect genetic studies,” said Daghlas, who graduated in May from Harvard Medical School.
More than 340 common genetic variants, including variants in the so-called “clock gene” PER2, are known to influence a person’s chronotype, and genetics collectively explains 12-42 percent of our sleep timing preference.
Chronotype is the natural inclination of your body to sleep at a certain time, or what most people understand as being an early bird versus a night owl.
Researchers assessed de-identified genetic data on these variants from up to 850,000 individuals, including data from 85,000 who had worn wearable sleep trackers for seven days and 250,000 who had filled out sleep-preference questionnaires.
This gave them a more granular picture, down to the hour, of how variants in genes influence when we sleep and wake up.
In the largest of these samples, about a third of surveyed subjects self-identified as morning larks, nine percent were night owls and the rest were in the middle.
This suggests that if someone who normally goes to bed at 1am, goes to bed at midnight instead and sleeps the same duration, they could cut their risk by 23 percent; if they go to bed at 11pm, they could cut it by about 40 percent.
It’s unclear from the study whether those who are already early risers could benefit from getting up even earlier.
But for those in the intermediate range or evening range, shifting to an earlier bedtime would likely be helpful.
How to wake up earlier
If you’re struggling to wake up in the morning, try keeping regular sleeping hours.
“This programmes the brain and internal body clock to get used to a set routine,” explains the NHS.