THE CLOCK
Built into our cells
The 2017 Nobel Prize recognised how a self-sustaining clock inside cells controls daily rhythms in sleep, hormones and body temperature.
How it worksStart
WHAT THE RESEARCH SAYS
When is
good for you?
Some of us wake bright at six. Others come alive at ten at night.
That difference is called chronotype, and it is partly written in our genes. Research on body clocks, from fruit flies to hundreds of thousands of people, explains why the best time of day is not the same for everyone.
LARK OR OWLit is partly genetic
Which one are you?Keep in mind
- Every cell keeps time
- Genes nudge the clock
- Age moves it too
- Know your own rhythm
THE SHORT ANSWER
Your clock is real,
and partly inherited.
Three findings, from a Nobel Prize
to a study of nearly 700,000 people.
THE GENES
351 places in the genome
A 2019 study of 697,828 people raised the known gene regions linked to being a morning person from 24 to 351.
See the numbers
THE CLASH
When clocks disagree
Jet lag is the clearest example. The NHS says daylight helps the body clock adjust to a new time zone.
Working with your clockWHICH ONE ARE YOU?
How did people
describe themselves?
UK Biobank asked 449,732 adults, aged 40 to 69 when recruited, whether they were a morning or evening person. Pick an answer to see how many chose it. The bar shows how common it was.
From the UK Biobank chronotype question, as reported by Jones et al. (2019). Shares are approximate.
TWO NUMBERS WORTH KNOWING
Many genes,
each a small nudge.
How many gene regions were found,
and how much they shift real sleep timing.
351
Regions linked to being a morning person
Using genetic data from 697,828 UK Biobank and 23andMe participants, researchers raised the number of known regions from 24 to 351.
GENE REGIONS · 2019
25 min earlier
Most vs fewest 'morning' variants
In 85,760 people who wore activity monitors, the 5% carrying the most morning-linked variants slept 25 minutes earlier on average than the 5% carrying the fewest.
SLEEP TIMING · 2019
The study estimated the heritability of chronotype from common genetic variants at 13.7%, so genes are only part of the story.
WORKING WITH YOUR CLOCK
Find a time
that suits you.
None of this changes who you are, but it can help you plan. These ideas come from the research and NHS advice on adjusting the body clock.
Step 1
Notice your natural timing
Chronotype is your preference for earlier or later sleep timing, so notice when you naturally feel ready to sleep and to wake.
Step 2
Get daylight to shift it
The NHS says natural daylight helps the body clock adjust, for example after crossing time zones.
Step 3
Be patient with teenagers
Research describes a shift towards eveningness in adolescence, easing back from the late teens and early 20s.
Step 4
For short trips, stay put
For 2 to 3 day trips, the NHS suggests you could keep your usual eating and sleeping times.
HOW THE CLOCK WORKS
A protein that
rises and falls.
In the 18th century, a French astronomer noticed that mimosa leaves kept opening and closing on a daily rhythm even in constant darkness. The word circadian comes from the Latin circa, around, and dies, day.
Working with fruit flies, the 2017 Nobel laureates isolated the period gene in 1984 and found that its protein, PER, builds up in the cell at night and breaks down in the day, switching off its own gene in a feedback loop. Cells in humans keep time on the same principles.
Questions
Questions on the way
What is a chronotype?
Your natural preference for earlier or later sleep timing. Researchers describe it as a behavioural sign of your underlying circadian rhythm, the roughly 24-hour body clock.
Is being a morning person genetic?
Partly. A 2019 study of 697,828 people found 351 gene regions linked to being a morning person, and estimated the heritability from common variants at 13.7%.
Why do teenagers stay up late?
Studies describe greater morningness in childhood, a shift towards eveningness in adolescence and a slow return towards morningness from the late teens and early 20s, thought to be driven by puberty and by schedules.
What does the body clock control?
The Nobel Assembly says it regulates functions such as behaviour, hormone levels, sleep, body temperature and metabolism, adapting our physiology to the time of day.
How can I reset my clock after a long flight?
The NHS suggests changing your sleep schedule to the new time zone as quickly as possible, going outside in daylight, and avoiding sleeping during the day.
Destination
Where the facts come from
- NobelPrize.org: The 2017 Nobel Prize in Physiology or Medicine, press release
- Jones et al. (2019), Genome-wide association analyses of chronotype in 697,828 individuals, Nature Communications
- Sleep-wake timings in adolescence: chronotype development and associations with adjustment (2021)
- NHS: Jet lag
Updated