They also have a knock-on effect. When we are sleep-deprived, weβre less likely to exercise because weβre tired. On the flipside, exercise can help us sleep better. Poor sleep affects our hunger hormones, dialling up our appetite and dialling down our bodyβs signals that we are full. And poor diet can, conversely, lead to a bad nightβs sleep by disrupting the neurotransmitters that control our circadian rhythm.
So, for the new study, Stamatakis and his team analysed the sleep, nutrition and physical activity data from the UK Biobank that tracked more than 59,000 participants over eight years.
Participants wore a device for one week, which captured their sleep and physical activity. They were also given a diet quality score (DQS) based on questionnaires about their intake of vegetables, fruits, fish, dairy, whole grains, vegetable oils, refined grains, processed and unprocessed meats, and sugary beverages.
On average, they found the risk of premature death was reduced by at least 10 per cent if people slept for 15 minutes more a day, plus did an additional 1.6 minutes of moderate-to-vigorous physical activity (MVPA) per day, and also ate an additional one and a half pieces of fruit or half a serving of vegetables per day β the equivalent of a quarter of a cup of cooked green vegetables like broccoli, spinach, carrots, pumpkin or cooked dried or canned beans, peas, or lentils.
This is the first study to examine the minimum β and hence likely more behaviourally sustainable β improvements across all three behaviours required for measurable improvements in health outcomes.
When separated out, the study found that achieving the same risk reduction by focusing on just one aspect would require significantly more effort. That is, 60 per cent more sleep or 25 per cent more physical activity. Just focusing on diet in isolation would not achieve a 10 per cent lower mortality rate. It also increases the chances of participants abandoning their efforts.
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βPeople tend to think they have to make massive changes, and they go very hard at it and then give up,β says Jon Buckley, the Executive Dean of the UniSA Allied Health and Human Performance Academic Unit at the University of South Australia. βThis study is reinforcing that if people can make small changes it can have a big effect on their health.β
Buckley adds: βYou donβt have to become an elite athlete, have a pristine diet or perfect sleep.β
For people whose sleep, physical activity, and diet were poor, combined increases of 75 minutes per day of sleep, 12.5 minutes per day of moderate to vigorous physical activity, and 25 points improvement in diet (five points equates to one less serving of processed meat per week, an extra half serving of vegetables or piece and a half of fruit) halved their all-cause mortality risk.
βThe take-home message is, relatively easy and modest improvements in these three components result in vast improvement in length of life,β says Professor Rob Newton of Edith Cowan University.
Those with the optimal combination of behaviours β seven to eight hours of sleep a night, between 42 and 102 minutes of MVPA a day and a good diet score β do not get the 10 per cent reduction in premature mortality risk for the same tweaks. However, those good behaviours alone corresponded to a 64 per cent lower risk for all-cause mortality compared with the least healthy group.
While this part of the study looked at lifespan, the next will look at health span.
Stamatakis encourages people to take it one step at a time when faced with health challenges they meet while theyβre trying to improve their lifestyle.
βEvery little bit helps when it comes to health behaviours: every extra bit of fruit, every extra serving of vegetables, every extra minute of moderate and vigorous activity,β he says.
βTry to make little, gradual changes towards your goals. This study and other studies point in exactly the same direction. There are large effects from subtle changes.β
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