Updated 16th December 2021

Going to bed earlier may prevent serious disease, ZOE study shows

In the largest study of its kind, ZOE researchers and their colleagues found that your bedtime impacts your blood sugar control and your responses to food the next day.

Previous research has linked bedtimes to risk of certain conditions, but the mechanisms behind sleep's links to heart disease, obesity, and type 2 diabetes has been unclear — until now.

Scientists from health science company ZOE — and their world-renowned academic colleagues who run the largest nutrition science study of its kind — may have found one of the missing pieces of this puzzle. 

Prof. Paul Franks and Dr. Sarah Berry discuss the research team's findings with ZOE co-founder Jonathan Wolf in the latest ZOE Science podcast:

The team’s latest research shows that your bedtime and how well you sleep significantly affect how well you can control your blood sugar levels the next morning. 

But why does blood sugar control matter? Good blood sugar control is important for your health. Large spikes and dips in blood sugar, on the other hand, are bad news. 

When they happen over and over again, they can put you at an increased risk of type 2 diabetes, heart disease, and obesity.

Previously, a study of over 88,000 people found that your bedtime is linked with your risk of heart disease.

The research — using data from the UK Biobank study — showed that people who regularly go to bed after 11 p.m. have a 12% higher risk of cardiovascular disease than those who go to bed between 10 p.m. and 11 p.m. 

Night owls, who usually go to bed after midnight, have a 25% higher risk.

The importance of bedtime and consistency

The ZOE research team and their international collaborators analyzed the blood sugar responses and sleep data of 953 people without any health conditions, who took part in a clinical trial called PREDICT 1.

The team published their results in the journal Diabetologia.

To allow the scientists to assess the participants’ sleep patterns in detail, the volunteers wore sleep trackers that picked up movement beyond what standard wearables are capable of. 

After a good night’s sleep — measured by looking at whether they managed to stay asleep for most of the night — the participants were generally able to avoid big blood sugar spikes after breakfast the following day. 

But when the participants didn’t sleep well, they experienced big spikes in blood sugar after breakfast, particularly if they opted for sugary foods.

Sleep efficiency, or how well you sleep, is clearly an important factor. But so is bedtime.  

People who generally had a later bedtime were less able to control their blood sugar the next morning, even if they slept in. Going to bed earlier, on the other hand, led to better blood sugar control. 

This means that you’re better able to control your blood sugar if you go to sleep earlier than you are if you try to catch up on sleep in the morning. 

Consistency is key because if you normally go to sleep early, staying up late for even just one night will make your blood sugar control worse the next day.

Unhealthy blood sugar responses can add up over time and may be one of the factors that contribute to the increased risk of cardiovascular disease seen in the latest UK Biobank study. 

But how is blood sugar linked to heart disease? 

High blood sugar is bad for the vessels around the heart, explained Prof. Paul Franks — a professor at Harvard University in Boston, MA, and Lund University, Sweden, and the senior author of ZOE’s latest research — in the podcast above.

Eating the right foods based on your sleep

After a bad or short night’s sleep, it’s natural to crave sugary breakfasts or drinks, said Dr. Sarah Berry in the podcast. She is an associate professor in nutrition at King’s College London and ZOE’s Head of Nutrition Science. 

As if that wasn’t bad enough, the lack of sleep and sugar interact, and the outcome for your blood sugar response is even worse. 

“Think about what breakfast to eat if you’ve had a bad night’s sleep,” Prof. Franks urged.

Avoid refined cereals, white bread, toast, croissants, and energy drinks, Dr. Berry said. She recommended reaching for foods that are higher in protein and healthy fats, like eggs and sourdough with avocado, rather than carbs.

“We now know that controlling blood sugar peaks and dips can have major effects on our body, such as tiredness, hunger, weight gain, and long term health conditions,” commented Prof. Tim Spector, a professor of genetic epidemiology at King’s College London and ZOE co-founder.

“I was surprised at the strength of the relationship we found in normal people — not just night shift workers or insomniacs. It shows how crucial even small changes in the timing and quality of sleep are for our overall health and well-being,” he continued. 

Improving sleep to improve health

Sleep is one of the pillars of good health and is easier to modify than others like exercise, Prof. Franks said. Dr. Berry’s key takeaway from the research was to go to bed 30 minutes earlier. 

Prof. Franks also recommended being mindful of what you eat for breakfast and considering healthier choices if you’ve slept badly, if you generally go to bed late, or if you’ve stayed up later than usual. 

“Everyone is different,” Prof. Spector said. “I believe everyone should experiment with their meal timings and sleep patterns to see what works best for them.”

“Simple and small changes to improving your sleep can have major impacts on the way your body responds to food and therefore your health.” — Prof. Tim Spector

At ZOE, we don’t believe in one-size-fits-all advice when it comes to your health. The ZOE program measures your blood glucose and blood fat responses, along with your microbiome, and helps you find the foods that work best for your unique body.

Take a free quiz to find out how you can learn which foods work best for you.