The study monitored the function of cells in various tissues throughout the day and found large shifts in activity just before dawn and dusk.
Researchers say the discovery could assist in medication, by timing doses to hit ‘sweet-spots’ in the body clock.
These body’s natural internal clock is known to drive massive changes, altering alertness, mood, physical strength – even the risk of a heart attack – in a daily rhythm.
A team at the University of Pennsylvania investigated the impact of the time of day on DNA function in mice.
They took samples from the kidney, liver, lung, aorta, brainstream, adrenal gland, cerebellum, brown fat, white fat, heart hypothalamus, lung and skeletal muscle.
Almost half of all genes involved in the manufacturing of protein altered their activity throughout the day.
Two major windows of fluctuating activity were observed in particular – dawn and dusk.
“I’m hopeful that we can use this information to design better therapies with existing drugs, and that’s huge because it’s not going to cost any more money,” lead researcher Dr John Hogenesch said of the findings.
“I think there is a real opportunity to improve current medication in a way that will be impactful,” he told reporters.
It is already well known that some medications work better when take at certain times of the day.
Heart disease, for example is driven by artery-clogging cholesterol, which is mostly made in the liver at night. Hence why taking satins in the evening makes them more effective.
The study’, published in Proceedings of the National Academy of Sciences, said 56 out of the top 100 selling drugs worldwide acted on genes that were known to be effective during these natural ‘rush hours’.
“If 40-50% of genes are going up and down over 24-hours and these are drug targets, then it’s going to be important,” said body clock scientist, Dr Simon Archer, from the University of Surrey.
“Thousands, millions of people potentially, could benefit from taking their medication at a different time of day and raising this kind of awareness is important.”
Body Clock – Find out what goes in your body throughout the day.
0.00-2.59 AM – Body shuts down
Sleep hormone melatonin peaking
Minimum levels of attention and vigilance
Brain washes itself and consolidates memories
3.00- 5.59 AM – Body fast asleep
Minimum core body temperature
Severe asthma attacks more common
Most natural births occur
6.00-8.59 AM – Slowly waking up – heart attack danger zone
Good time to wake up
Heart attacks more likely
Men have their testosterone peak
9.00-11.59 AM – Most alert
Maximum cortisol levels
Best short-term memory
12.00-2.59 PM – Biological siesta
Increased gastric activity
Post lunchtime dip in alertness
Surge in road deaths
3.00-5.59 PM – Go exercise!
Best lung & cardiovascular performance
Core body temperature rising to its peak
Good time to exercise
6.00-8.59 PM – Watch what you eat
Poor time to eat a big meal
Liver handles alcohol better
Intuitive thinking is better
9.00-11.59 PM – Ready for sleep
Melatonin production building
Core body temperature dropping
Good time to go to sleep