When 7 hours of interrupted sleep seems about as likely as winning the lottery, you might begin to wonder if it’s just the way you are.
Perhaps you’ve tried everything under the sun (and moon) to sleep better, but nothing seems to help you get the rest you need.
Is there something you can do though, or are your sleep problems firmly inscribed in your genetic code?
The reality may be that it’s a bit of both. Most people can improve their sleep by adopting more positive sleep habits. Equally, scientists are increasingly finding links between genetics and sleep characteristics.
Can genes really affect our sleep?
Scientists haven’t proven beyond doubt that genetics can explain all sleep characteristics and disorders. But the evidence of a connection in some cases is mounting.
A report from The National Center for Biotechnology Information reviewing a number of studies found that:
It is now clear that sleep is genetically controlled. Although environmental factors can impact the duration and intensity of sleep, genetic regulation is borne out by the heritability of sleep trait
However, there don’t appear to be specific genes whose sole purpose is to control sleep. But a number of genes do have a part to play in the functioning of our internal body clock. And genes might play a role in some sleep disorders.
Early bird or night owl
Whether you prefer to go to bed early and rise at the crack of dawn (an early bird), or stay up late and sleep in (a night owl) could be due to personal, lifestyle or work reasons. But it may also be genetic.
In February 2016, a team of researchers reported that:
a genome-wide association analysis of 89,283 individuals identifies genetic variants associated with self-reporting of being a morning person.
They identified 15 genes which impact on the circadian rhythm, and could be associated with deciding if you’re a morning or night person.
There are also studies which suggest that morning people suffer less from insomnia, weight gain or depression. But whether that’s also genetic still isn’t clear, and the study above didn’t report conclusive associations.
Surviving on less sleep
You may have heard about some of the famous people who seemed to function well on just a few hours sleep.
Winston Churchill, the famous wartime British Prime Minister, is an often quoted example.
However, it’s estimated that only about 1% of the world’s population are genuine short sleepers, defined as being able to get by on between 4 to 6 hours sleep every night.
So did these short sleepers train themselves to get by on so little sleep, or is it a result of their genetics?
In 2009, researchers at the University of California discovered that two short sleepers had a rare gene variation, called hDEC2. It’s a very small sample, of course, and more research will need to be done.
Twin study of short sleepers
In 2014, researchers looked at sleep patterns and performance in 100 pairs of twins.
They found that a variant of the BHLHE41 gene was prevalent in the individuals who slept on average just 5 hours per night. And twins without the gene variant slept for more than an hour longer on average.
The researchers also compared the mental performance of the different twins over a period when they were deprived of sufficient sleep.
Those with the gene variant made 40% fewer mistakes and took less time to recover.
Genetics and insomnia
In June 2017, a group of researchers conducted a large gene study involving 113,006 people. One of their conclusions was that they identified:
three loci and seven genes associated with insomnia complaints, with the associations for one locus and five gene
Whilst this might not mean much to the lay reader, it does provide further evidence of a link between genetics and insomnia.
And in 2018, researchers confirmed that insomnia has a partially inheritable element. They looked at the DNA of 33,000 soldiers in the army, and found that insomnia was linked to specific variants on chromosome 7.
They also found a genetic link between insomnia and type 2 diabetes. And in Europeans, they found a link between insomnia and major depression.
Poor sleep and seasonal depression
It’s estimated that around 6% of Americans suffer from Seasonal Affective Disorder (SAD).
And a survey carried out in the UK suggests that the number suffering from mild SAD during the winter may be even higher – as much as 1 in 3 people.
This can result in depression-like symptoms during the darker winter months. Although the reasons aren’t fully understood, it’s thought that the lack of daylight affects your natural circadian rhythm.
Some people suffer from both SAD and poor sleep. In January 2016, a group of scientists from the University of California found that a rare variant of the Period3 gene occurred in two people suffering from SAD and poor sleep.
They also conducted tests on mice which appeared to support the link between these two conditions and the Period3 gene.
One of the study authors, Profesor Ying-Hui-Fu, said:
It’s an exciting time. People have known for decades that light and mood were linked, but this is our first real finger-hold on the problem.
Changing sleep patterns as you get older
In December 2015, a group of scientists at the University of Pittsburgh reported how genes associated with your internal body clock altered as you get older.
They went on to describe how this could be linked to changes in older people’s sleep patterns, such as becoming more of a ‘morning person’. Dr. McClung said:
As we expected, younger people had that daily rhythm in all the classic ‘clock’ genes…But there was a loss of rhythm in many of these genes in older people, which might explain some of the alterations that occur in sleep, cognition and mood in later life.
Sleepwalking and sleep terrors run in the family
- Children had a 22% chance of sleep walking when neither parent had a history of it.
- If one parent sleep walked as a child, the chance increased to 39%.
- If both parents had sleep walked, the chance of their children sleep walking was 61%.
Dr. Montplaisir commented:
These findings point to a strong genetic influence on sleepwalking and, to a lesser degree, sleep terrors…This effect may occur through polymorphisms in the genes involved in slow-wave sleep generation or sleep depth.
Can poor sleep affect your genes?
It’s not always immediately obvious if a lack of sleep leads to ill health, or if an illness is causing the sleep problems.
And it could be that a similar conundrum exists with the genetics of sleep. A 2013 study led by the University of Surrey in England, looked at whether poor sleep could have an impact on our genes.
In this small laboratory based study, 12 healthy women and 14 healthy men slept for less than 6 hours one week, and then more than 8 hours another week.
At the end of each week, researchers examined their blood samples that included RNA, or ribonucleic acid. RNA has an essential role in generating proteins, a fundamental life process.
With these blood samples, the researchers were able to look at what happens to the RNA in the brain, liver and blood.
The researchers found that with less sleep, there were changes to 711 RNA genes associated with our ability to fight inflammation, disease, and stress.
The evidence that our genes might influence how well we sleep is mounting. And genetics appear to be a risk factor for certain sleep disorders. Some other statistics supporting a ‘runs in the family’ premise include:
- If your father was a night owl, you’re twice as likely than average to also be a night owl.
- 75% of people suffering from Restless Leg Syndrome have a family history of the problem.
- You have a 60% chance of sleep walking or having sleep terrors if both parents also did in their childhood.
Equally, it’s well known that many other factors such as stress, anxiety, illness and diet can have a marked effect on the quality of your sleep.
Of course, knowing that you might have a genetic disposition to sleep differently is unlikely to solve the problem, at least for now.
But perhaps in the future, a better understanding of the genetic factor will play a role in how sleep disorders are treated.
Do sleep problems run in your family? If so, it would be great to hear from you in the comments below.