Sleep
March 13, 2019
You probably know about how genetics play a role in eye color, height, even heart health.
But did you know your genetics play a role in your penchant to sleep in or rise early?
Benjamin Franklin famously said: "Early to bed and early to rise, makes a man healthy, wealthy, and wise"
While this life philosophy probably worked well for him, modern research has found that there are in fact morning people and night owls. Sometime very successful and productive people work best at night.
Famous examples include Charles Darwin and Winston Churchill.
Source: If You Want To Get Ahead, Be a Night Owl
What hasn’t been clear was whether this was a result of nature or nurture. Do morning people get up earlier out of habit, or is it in their genes?
It turns out the answer is all of the above.
Much of our sleep wake cycle is outside of our control. Work, kids, spouses, and our commutes all seem to play a bigger role in dictating our sleep schedules than our own preferences.
A new study shows that there are genes associated with being a morning person. Researchers correlated genome data from 696,828 people from the UK Biobank and 23andMe, a genetic testing company, to find genes correlated with being morning people.
They found 351 genes that had significant correlations. The people carrying the most "morning people genes" slept about 12 minutes earlier than average. People carrying the most "evening people genes" slept about 12 minutes later than normal.
Genes associated with being a morning person also happened to help control your body's rhythm. Many were found to be involved in your circadian rhythm, which is your body's way of maintaining a consistent schedule through the day.
When you stay up past your normal bedtime and you start to feel sleepy, that is your circadian rhythm telling you that it's time to sleep.
One of the most important features of the circadian rhythm is your melatonin levels. Melatonin is a hormone that helps you feel sleepy or awake. As you can see in the chart above, its concentration varies dramatically though out the day. Its concentration increases by more than 1000% just before bedtime and falls just before you wake up.
Source: Novel melatonin-based therapies: potential advances in the treatment of major depression
Researchers found some surprising correlations between morning people genes and disease.
Genes associated with general well-being were positively correlated with the genetics of morning people. This means that some of the same genes that help determine your sleep time also help determine how happy you feel.
Similarly, "morning people genes" are also negatively correlated with depression genes. If you have a lot of morning people genes, you are slightly less likely to have depression genes.