Your body clock tells you the best time to sleep, eat and have SEX – expert reveals how to work out when’s best for you
CAN you work a night shift and still get enough rest? It is all to do with your body clock. And a new book shows us how our internal clock controls everything we do.
Russell Foster, Professor of Circadian Neuroscience at Oxford University, and author of Life Time, says: “Our body needs the right materials in the right places at the right times, and our body clock provides this structure.
“A master clock in the brain regulates clocks throughout the body. It’s like an orchestra, and if you lose the conductor (the master clock) then the musicians play at the wrong times.”
Here, he answers questions about our body clocks.
- Life Time, The New Science Of The Body Clock, And How It Can Revolutionize Your Sleep And Health, by Russell Foster (Penguin Life) is out now, priced £16.99.
HOW CAN YOU BEAT JET LAG?
OUR internal clock is set to the external world by light, but the effects of light vary. Morning light advances the clock and makes you get up earlier, while dusk light delays the clock and makes you get up later.
Read more on sleep
If you’re flying west from the UK to New York, you should seek out light upon arrival. The light will hit your clock when it “thinks” it is dusk in the UK and the clock will be delayed to New York time.
Going east from the UK, say to Australia, you need to advance your clock. Avoid morning light – a pair of good sunglasses will do the trick – and seek out late-afternoon light for the first few days.
By late afternoon in Sydney, it will be morning in the UK, which will advance the clock to the new time zone. There are apps that tell you when you should seek out light after crossing time zones.
WHY DO TEENAGERS SLEEP SO LATE?
THERE are three key factors that determine sleep patterns. Firstly, genetics help determine if you are an early bird (a lark), a night owl or an intermediate (a dove).
Most read in Health
Hormones also play a part. From age ten, there is a tendency to go to bed later, which peaks in our twenties before declining. This follows the rise and fall of oestrogen and testosterone as we age.
On average, someone in their sixties will go to bed two hours earlier than a teenager.
The third factor is light. If a teen oversleeps, they miss morning light, which advances the clock.
Evening light delays the clock. To fix the cycle, use an alarm to get bright morning light.
DO WE NEED BEAUTY SLEEP?
CORTISOL, the stress hormone, has its own circadian rhythm. It is high when we rise and stays high for a few hours before decreasing.
Cortisol breaks down collagen – the connective tissue in your body – and increases water retention.
That’s why you can look puffy in the morning.
Stress is the enemy of sleep. Many people don’t have a sleep problem – they have a stress problem.
WHEN SHOULD WE STOP DRINKING COFFEE?
THE timing of the sleep-wake cycle is down to the body clock and sleep pressure, which means the longer you’ve been awake, the greater the need for sleep.
Adenosine, the sleepy hormone, builds from waking up, increasing sleep pressure.
But caffeine blocks brain receptors that detect adenosine, so coffee makes you feel more awake.
As caffeine stays in your body for up to nine hours, you shouldn’t drink it in the afternoon if you want to sleep well.
WHY ARE PROLONGED NIGHT SHIFTS BAD FOR YOU?
THE body does not adapt to working nights as it activates the stress axis. This is useful in short bursts, but it’s like driving a car in first gear – too much and it will destroy the car.
People who work prolonged night shifts are more likely to be obese and have Type 2 diabetes. They will also be at greater risk of high blood pressure, cancer, depression, reduced immunity and mental illness.
Night-shift workers should have more frequent health checks and access to protein-rich, low-fat snacks while at work.
WHAT TIME SHOULD YOU TAKE MEDICATION?
STUDIES show some medication has a better effect if taken at a certain time of day.
For example, there is a 50 per cent greater chance of having a stroke between 6am and noon.
But if you take your medication in the morning, it’s too late. You should take it in the evening, ready for that blood pressure surge the following morning.
People using aspirin to thin the blood should do so in the evening as blood platelets are made fresh each night. Studies also show some vaccines are more efficient in fully rested individuals.
WHEN TO TRY FOR A BABY?
IF you are hoping to conceive, you need to have sex in the three-day window before ovulation. During this period, women are more attracted to male attributes.
Similarly, men are more attracted to women as they approach ovulation.
Testosterone can be 50 per cent higher in the morning than later in the day, and sperm are likely to be more mobile.
However, women are less inclined to have sex first thing in the morning, but this could be because of societal pressure on them to get up and out.
WHY DO WE WAKE UP MORE TO USE THE TOILET AS WE AGE?
AS we get older, our sleep becomes less deep and the rhythms driven by our body clock compress.
Hormonal cycles controlling urine production should turn on in the day and off at night. But as the cycle becomes more compressed, we may start to make urine at night.
Another reason is that if you sit down a lot during the day, fluid will accumulate in your legs. When you lie down, this fluid is distributed throughout the body, which can make it into urine to expel it.
WHAT’S BEST TIME TO EXERCISE?
DURING the day, we consume and burn calories. At night, we burn stored calories from fat.
If we exercise before breakfast, we are burning stored calories, meaning you are more likely to lose weight than through exercising later on.
READ MORE SUN STORIES
Read More on The Sun
But because our body temperature rises during the day, we can sustain more rigorous exercise in the afternoon and evening.
So, for some people, late afternoon exercise burns more calories. The ideal would be a bout of exercise pre-breakfast, and more vigorous exercise later in the day.