What’s the latest research on eating and sleep?

There’s been a lot of research in the last few years on the interaction between eating and sleep. Dr David Cunnington and Kris Pierce discuss the latest research and strategies for eating well for better sleep and the effect of eating habits on sleep.

Audio Timeline:

  • 00:00 – 01:59 Impact of poor sleep on weight
  • 01:59 – 04:30 When we eat more important than what we eat
  • 04:30 – 06:05 What should people do?

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Kris Pierce: So David, we’re here this week. We’re talking about sleep and weight. In one of your earlier posts this week, you wrote how poor sleep has an impact on weight. Why does this occur?

David Cunnington: There are lots of potential reasons why poor sleep can have an effect on weight. There have been models in a research setting to show that both – even if we take people and don’t let them sleep well on one single night and sleep deprive them for one night, then let them go to the buffet the next day, they will take a lot more calories. They will take a lot more starchy food, a lot more salty food. So just one night of not getting enough sleep can really have an impact on appetite but also what sort of food we’re looking for.

Then there has been some other work which is a more real world sort of experiment where people have been chronically partially sleep-deprived and that means just not allowed to get quiet enough sleep each night, so about five hours sleep each night, not dissimilar to what a lot of us are doing in our sort of busy day to day lives.

That also showed that if they went to the buffet or were allowed to just eat as they wished, they took a lot more calories than people that were sleeping for seven hours per night or more.

Just that amount of calories, around 500 calories per 24 hours adds up to a lot in terms of extra weight gain over a year. People who have got insomnia also get some changes with their appetite. We think part of that is tied up in the way the adrenaline system works. So there are some factors about insomnia, as well as not getting enough sleep, that turn on the body’s sort of primitive fight-flight response or adrenaline response and that adrenaline response makes us look for more energy. It also changes the way the body handles energy. So it means that energy is being mobilised, being circulated around the body as higher blood sugars, which can have an effect on our appetite rather than necessarily being burned.

Kris Pierce: One of your other points was when we eat may be more important than what we eat. Why did you say that?

David Cunnington: For years, we’ve been very focused on what we eat, lots of guidelines about diet and lots of fad diets really to be honest. None has really been successful and they’ve come and gone the last 30 years really. We’ve brought in the food pyramid and calorie counting and more recently Pritikin diet and a whole range of other diets. Have they been successful? Well, if you look at the population and obesity rates, you have to say no. Western populations, we’re just getting heavier and heavier and obesity is just getting worse and worse despite these diets being in place.

Some of the basic research that’s coming out about energy and sleep really shows that when we eat, in terms of our body clock and in terms of timing across the day, has a major factor in how the body handles that energy. A really interesting experiment that just got published in December last year where groups of mice were given the same amount of calories. Some were allowed to eat only in a 12-hour window each 24-hour period whereas others were allowed to eat whenever they liked across the 24-hour period. So even though they ate the same amount of calories, those that ate outside of a 12-hour window gained a lot more weight and turned into overweight, unhealthy mice. Whereas even if you’re fed an unhealthy diet but constrain those mice to within the 12-hour period, they didn’t gain weight and they remained healthy.

That has really been preceded by work over about the last five years where there has been lots of experiments looking at the timing of food and the timing of when we take calories playing an important role in how the body handles it. If we’re taking food at times when the body is not ready for it or is not part of our regular routine, it can really increase our blood sugar levels, give us an increased risk of diabetes, increased risk of cardiovascular disease.

So that’s the basic science data. But then when you take to the real world and you look at how a lot of us are behaving around food in the real world – and over that same 30 years where we’ve had obesity increasing despite diets, a lot of our behaviour around food has become more eat-on-the-run. It’s erratic. So maybe we need to get back to that more regular routine, eating at predictable times, predictable portion sizes at predictable times, which may go a long way to what’s helping with controlling weight and it would be a more healthy approach to eating particularly as it relates to sleep.

Kris Pierce: So what should people do? What’s the practice approach for people out there who are trying to manage their weight and sleep?

David Cunnington: I really like what you wrote in your blog things like eating whole foods, keeping an eye on portion size, making sure you have regular meals and particularly breakfast and getting sort of started with breakfast.

For me, I do think it’s about the timing. I think if I’m looking for where research really can guide us in terms of what we could do around healthy eating and sleep, regular meal times I think is the thing that’s starting to come through in research as being one of the real keys.

Around 50 years ago, there was a treatment for depression as a behavioural treatment called social rhythm therapy and it was recognised that people with depression often are quite chaotic in terms of their activities during the day and meals as well.

Part of social rhythm therapy was actually just getting people back into a regular routine with activities and meals. That was very effective at managing symptoms of mood and general well-being. Fast forward 50 years and that sort of treatment to me was really a circadian rhythm treatment. Not recognised as that at the time but I think in this day and age where again our lives are often characterised by chaos, unpredictability, doing things on the run, getting back into a more regular routine just allows our body to get used to handling energy in the way it’s supposed to handle energy.

Kris Pierce: That’s great advice.


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