Dr Yu Sun Bin

Expert Q&A Introducing: Dr Yu Sun Bin

1. Could you tell us a little about your career and areas of expertise/interest? 

I work as a research fellow and senior lecturer in sleep and circadian health. My research is focused on how sleep and circadian rhythms affect the health of the community as a whole, and my teaching is focused on raising awareness of how important sleep and circadian rhythms are for health and wellbeing. I am particularly interested in how to promote sleep as a healthy habit; the impact of sleep disorders in pregnancy and in women more generally; and also applying circadian science to reducing jetlag.  


2. What drew you to this line of work/research in the first place?

I went to uni thinking I would be a physicist! But I found psychology, particularly the ways of thinking and behaving that we all have in common as humans, more interesting. Since I wanted to focus on the things that people have in common, I was not interested in practicing (clinical) psychology, I was interested in how we can improve health for everyone. This is why I went into further study in public health, because it is all about how the environment we live in affects our health. By environment, I mean all aspects of the environment from our culture, values, and institutions, as well as the built and natural environments. 

Sleep is a great example of something we all do and have in common, which is heavily influenced byhow much we value sleep, when we sleep, and who we sleep with. As a society, we are just beginning to realise how cultural changes in technology and work hours negatively affect our sleep, but we haven’t yet found systemic solutions to preserve sleep and our health.


3. How do you look after your own physical and mental wellbeing?

I get enough sleep and try to be realistic about what can be accomplished in one day. I know that if I over-work, I will only need to spend the next day recovering, rather than having gained extra time! I have learned to be more consistent in my work patterns and to try and approach life as one long marathon where I’m NOT in a hurry to get to the end.


4. Do you have a favourite post-workout cafe?

I think that question assumes I work out! I’m not a fan of gym-based exercise, but a big fan of walking everywhere and long walks with my dogs. I find that a coffee beforehand helps with my motivation to start and my ability to keep going; but no caffeine is needed afterwards. 


5. What is one thing you wish people knew about wellbeing? 

There are no secrets and we’ve known what works for a very long time! For sleep for instance, it’s well documented in the Bible – a text that is thousands of years old – that people knew that sleep deprivation was harmful and understood that insomnia was caused by stress and anxiety. They also understood that alcohol can negatively affect sleep while exercise could improve sleep. 

We also have more recent evidence from the late 1890s, more than a century ago now, where people lamented in medical journals that there was more insomnia due to “the busy-ness of modern life” but that same comment is often made today. Neither the problems nor the answers have changed; we just need to be better at implementing those boring old answers and stop looking for panaceas. 


6. What is one of the most ridiculous things you’ve read or seen about wellbeing that you know to be untrue? 

I try not to repeat things that I know to be untrue. Unfortunately with the way that modern media and social media is designed, commenting on untruths only tends to spread them further!


7. Do you have any favourite books, podcasts or websites on health or wellbeing that you’d recommend?

I think reading books and listening to podcasts you actually enjoy is best for wellbeing! I personally enjoy listening to these podcasts:

  • No Such Thing as a Fish, in which the QI researchers discuss random facts in a light-hearted fashion
  • The Junkees , in which comedians Kitty Flanagan and Dave Hughes talk about and taste-test junk food (everything in moderation!)
  • Swindled, in which an anonymous American narrator with a very dry sense of humour talks about white-collar crimes and institutional and regulatory failures


8. What is your top tip for living a healthy and happy life? 

Spend time outdoors! Apart from getting natural light that is essential for quality sleep, there’s also a whole wealth of research that shows that seeing and being surrounded by greenery, sky, and water provides people with a sense of restoration. We don’t know why exactly, but surely 50 million years of primates living and evolving in natural environments has something to do with it!

Research Review: Can We Sleep To Much?

In this article, our expert Dr. Yu Sun Bin reviews: Can People Sleep Too Much? Effects of Extended Sleep Opportunity on Sleep Duration and Timing by Klerman EB, Barbato G, Czeisler CA, Wehr TA. 


1) What was the high-level summary of the research? 

People cannot sleep ‘too much’. The amount of sleep we get is regulated by the homeostatic and circadian systems which drive us towards a stable amount of sleep, provided we allow enough time for it. 

While we cannot sleep too much, we can spend excess time in bed. When given 12-14 hours of opportunity to sleep, healthy people can develop patterns similar to those with insomnia and take longer to fall asleep, wake more often in the middle of the night, and wake too early and be unable to go back to sleep. 


2) What did the study try to measure? 

The study measured objective sleep using sleep studies. The study assessed whether, when given long periods of time in which to sleep, people could sleep to excess, or if they would reach a stable point with a roughly consistent amount of sleep every night. 


3) How was the study undertaken? 

The authors of this study analysed data from two of their previous studies. 

In Study 1, healthy volunteers were given the opportunity to spend 14-hours in bed per night for 28 days; In Study 2, volunteers were given the opportunity to spend 12-hours in bed for 8 nights, with the addition of a 4-hour window for napping during the day. 

Neither study interfered with the sleep of the volunteers, apart from giving instructions that they should try to sleep during those windows of time. Both studies involved volunteers sleeping in research labs so that factors such as work and socialising did not influence how much volunteers slept and when they went to sleep and woke up. 


4) What did the study find? 

In both studies, volunteers slept more during their first week in the lab – on average, sleeping 2 hours longer than they did at home. However, the differences between volunteers were marked: some did not sleep more at all when given the opportunity, whilst others slept almost 6 hours longer! 

After the first week of extended opportunity for sleep, the total sleep time of the volunteers stabilised: on average, people in Study 1 slept 8.6 hours nightly, whilst those in Study 2 slept 8.9 hours on average. However, individual needs for sleep were very different: at one extreme, one volunteer stabilised at 5.2 hours of nightly sleep, whilst at the other extreme, another stabilised at 11.0 hours. These results show that during the first week in the lab, having protected sleep time was important for many of the volunteers to catch up on sleep. However, once they had caught up, their sleep stabilised and they tended to have roughly the same amount of sleep every night. This amount of sleep was unique to them.

Also important to note is that sleep quality decreased for many of the volunteers in these studies – that is, even though the same amount of sleep was achieved, it took them longer to fall asleep, they woke up more often or too early on some nights. However, unlike people with chronic insomnia, these healthy volunteers then made up for this slight sleep loss the next night. This is exactly how sleep is supposed to work as dictated by the sleep homeostatic process which maintains an equilibrium in our sleep/wake cycles. 


5) Is there any other research out there that supports these findings or contradicts it? 

There is plenty to support it! For example, in large scale epidemiological studies that link long sleep durations (>9 hours) to poor health, the association is no longer seen when existing health conditions are taken into account. This suggests that it is time in bed and poor sleep quality that contributes to poor health, or that poor health contributes to excess time in bed and poor sleep quality.

Similarly, in terms of performance, it is not possible to sleep more to ‘bank’ sleep, but it is possible to reduce existing sleep debt so that you are better protected from any effects of future sleep deprivation. 


6) How much weight should we give this research?

This research is highly credible given the supporting evidence. The only thing to keep in mind is that the studies were limited to young people, aged 18 to 36 years, without any health conditions so the expectation of ~8 hours of sleep being average may not be applicable to other age groups and people with existing health conditions.


7) What does this mean for your work/research/industry? 

There is often a disconnect and conflict in the sleep field about what advice we give to people with clinically significant insomnia and to the general public at large. The message we try to give to the general public is that typically, people should sleep more to get enough sleep. However, the clinicians who work with insomnia sufferers are unhappy with this message, because spending more time in bed can make insomnia worse. 

This study shows that there is a direct connection between those two messages and that they are actually not in conflict. That is, we should all try to sleep enough, for us to be individually well-rested, but avoid spending more time in bed beyond that point, because it only creates poor sleep quality that’s similar to symptoms of insomnia. 


8) What’s the key takeaway for us to take from this research?

It isn’t possible to sleep ‘too much’ but it is possible to spend too long in bed. If you spend too long in bed, the quality of your sleep can suffer. 


9) Will you be doing anything differently because of this research? 

I think this study highlights we should give ourselves the opportunity for enough sleep every night and try to figure out where our equilibrium point of ‘enough sleep’ is. We should then try to protect our sleep time to achieve our required amount of sleep as much as possible.


Dr Yu Sun Bin is an epidemiologist and public health researcher. Her particular research interests are on sleep and circadian rhythms and how these biological systems are reflected in behaviour, health, and disease.

6 Evidence-Based Strategies For Optimising Your Sleep

Most researchers agree that adults need at least seven hours of sleep each night for proper cognitive and behavioural functions. Talk to people around you though and chances are many of them will identify sleep as something they struggle with. Like diet and exercise, sleep has a huge impact on our wellbeing. The good news is, we can actively work on our sleep habits and improve them. Sleep researcher, Dr Yu Sun Bin offers these 6 strategies for optimising your sleep.

#1 – Stick to a Sleep Schedule

Our circadian rhythm has a direct influence on when melatonin (the body’s sleep hormone) is released to help induce sleep. If your circadian rhythm is out of sync with the natural cycle of day and night, it can make it harder to fall asleep. 

The circadian rhythm is influenced mainly by light and dark, but also by your daily activities. Sticking to a consistent sleep cycle can help you avoid what is referred to as social jet lag. Social jet lag occurs when the time you want to go to sleep as dictated by your internal body clock doesn’t align with your actual sleep patterns due to work or social commitments.

To ensure your circadian rhythm stays in sync, try to stick to a reasonable and consistent time you go to bed and wake up every day, including weekends.

#2 – Take That Nap!

Life has its ups and downs and sometimes not being able to get enough sleep is out of our control. The good news is that naps are science-approved. It’s important to understand though what constitutes a good nap, when to nap, and how long we should be napping to avoid waking up feeling groggy or having sleep inertia. 

To increase alertness, the best time for most people to nap is between 2-4 pm, after your morning peak and as alertness is starting to decline. If you are sleep deprived, it’s generally good to get a nap earlier in the day. Science shows us that the ideal nap is generally short, between five to thirty minutes, with a ten-minute short nap having the best immediate benefit. 

The key to napping is keeping it light. You don’t want to allow your body to fall into a deep sleep, so set an alarm to wake up.

#3 – Avoid Caffeine in the Afternoon

Caffeine presents in the brain as a molecule similar in structure to adenosine, a chemical that builds up in the brain when we’re awake and affects how sleepy we feel. When we consume caffeine it blocks the receptors in the brain that normally receive the adenosine molecule, making us feel more alert. Once the caffeine wears off, the adenosine molecule re-attaches to the receptors, putting a sudden break to brain activity and making you feel tired or sluggish. 

Half the caffeine we consume is metabolised in about six hours. If you have a regular flat white at 2 pm, half of the caffeine will still be present in your system at 8 pm. This explains why drinking caffeine in the afternoon can disrupt your ability to fall asleep. 

To optimise your sleep, try to avoid caffeine after 2 pm, and if you would like to cut back on your caffeine intake, do it gradually to avoid withdrawal symptoms such as headaches.

#4 – Reduce Alcohol Intake

Many of us get caught in the alcohol sleep paradox and don’t even realise the effect it is having on our bodies. What is the alcohol sleep paradox you ask? Drinking alcohol is known to help us fall asleep, but what most people don’t realise is that it also contributes to disturbed sleep patterns as it increases our waking throughout the night. 

For the average adult who sleeps for eight hours a night, just four standard drinks can deprive you of ~50 minutes of quality sleep. 

#5 – Exercise Outdoors & Synchronize your Circadian Rhythm to Daylight

We all know that exercise has numerous health benefits. Yet not everyone is aware of the relationship between exercise and sleep. For instance, exercising at night can delay your bedtime as your body needs to lower its core temperature after exercise in order to induce sleep. 

Try fitting your higher intensity workouts in the morning when you first wake and stick to lower intensity workouts like light yoga in the evening to help you optimise your sleep.

#6 – Eat a Healthy Diet

Eating a healthy diet can help you optimise your sleep. Increase your intake of fish and whole foods that contain lots of protein and fibre. Protein and fibre contain an important amino acid called tryptophan which is used to produce melatonin, the human sleep hormone. 

Try to eat your dinner more than three hours before bedtime to give your body enough time to register that it’s full and allow you to metabolise your food properly.


Dr Sun Bin is an epidemiologist and public health researcher. Her particular research interests are on sleep and circadian rhythms and how these biological systems are reflected in behaviour, health, and disease.

Research Review: The Impact of Sleep on Self-Control

sleep and self-control

In this article, our expert Dr. Yu Sun Bin – reviews: Sleep and self-control: A systematic review and meta-analysis by Guarana et al 2021. 


1) What was the high-level summary of the research?

The quality and duration of our sleep affects our levels of self-control i.e., our ability to control our impulses and overcome temptations.


2) How was the study undertaken?

This study was a systematic review, which means that the researchers comprehensively searched the scientific literature for studies on sleep and self-control to try and synthesise (bring all of the evidence together to summarise) what we currently know and to identify where more research might be needed. 

The team of researchers then sorted through more than 1600 studies, focusing in on studies that tried to answer the question of whether sleep affects self-control. Specifically, the researchers used meta-analysis which means that they combined the numerical results from the studies to find an overall result. This overall result should be more reliable and more indicative of the true effect of sleep on self-control than the results of individual studies, which can be ‘noisy’ and throw up unusual findings by chance. 


3) What did the study find?

The researchers found 56 studies on sleep and self-control.

Researchers tend to think of self-control in two ways: first, as a somewhat stable trait of a person (akin to personality), and second, as something much more fluid, like a state-of-mind which can change from moment to moment (like mood). 

These two ways of thinking about self-control are important when it comes to understanding the results.

When the researchers examined the studies that considered sleep and self-control as stable traits, they found that people who get more sleep tend to have better self-control than people who get less sleep but that this was a weak relationship (correlation r=0.17*).

Similarly, people who have better quality sleep have better self-control than people with poorer quality sleep (r=0.26), this relationship is stronger than the one between sleep duration and self-control, but is still considered a weak to moderate strength relationship. This could be because there are other factors responsible for both better sleep and for self-control (e.g. shared genes); or could be due to reverse causality, that is because people with better self-control are also more organised and conscientious about their sleep habits, leading to better and more sleep on average. This result is less useful for us as individuals because we might not be able to change how much sleep we need personally or our personality.

When the researchers examined the studies that consider sleep and self-control as malleable states, both longer sleep duration and better sleep quality were again related to high levels of self-control (r=0.32, and r=0.35 respectively). This is the more important practical result, because it shows that when we have a good night’s sleep, we have a higher level of self-control the next day, compared to when we have a poor night’s sleep or not enough sleep.

Both of these relationships were stronger than the relationships we see for self-control as a trait, meaning that our self-control changes more in response to how our sleep changes from day-to-day, than differences in levels of self-control between people who naturally need different amounts of sleep. 

It is important to note that the majority of studies relied on research participants to self-report their sleep which might lead to biases in the results. However, the researchers also found that the relationship between sleep and self-control was stronger when sleep was measured objectively, indicating that the results are not due to the way that people report or perceive their own sleep. 


4) Is there any other research out there that supports these findings or contradicts it?

The broader scientific literature supports these findings. We know that when people are sleep-deprived, our ability to monitor our own thinking and behaviour is negatively affected. Lack of sleep particularly affects activity in the prefrontal cortex, which is the part of the brain responsible for our ability to be aware of our own thinking and to control conscious actions. Self-control involves being aware of our instincts (e.g. to have more cake) and to actively overcome those instincts (e.g. to tell ourselves we have had enough and to put away the cake for another day). 

The results of this study also show that sleep quality is more important than sleep duration when it comes to self-control. This is supported by research showing that quality of sleep is generally more important than amount of sleep for wellbeing; shorter sleep durations (e.g., 6 hours a night) may not be a bad thing if it is accompanied by good sleep quality. This is because people can have a range of different sleep needs, with 7-9 hours of sleep opportunity recommended for working-aged adults


5) How much weight should we give this research?

We should give the results of this study a lot of weight, because it systematically combines all the research that has been done so far on how sleep affects self-control. The main potential weakness of the study is that 32 of the 56 studies were correlational studies and these studies only show that sleep and self-control are correlated, not that sleep directly causes changes in self-control. With correlation studies, we cannot rule out the possibility of reverse causality i.e. that self-control causes better sleep. In the remaining 24 studies, researchers actively intervened to change the quality and duration of sleep in the research participants.


6) What does this mean for your work/research/industry?

This study opens up some interesting avenues for research. Having self-control is important for many aspects of life, including maintaining our health and for our success at work. It suggests that we should consider improving sleep as a way to improve people’s ability to self-regulate which in turn can enhance health and productivity. For health researchers, it suggests we should incorporate methods to improve sleep in programs that help people quit smoking or lose weight, as this could make them even more effective. 


7) What’s the key takeaway for us to take from this research?

The key takeaway is that having good quality sleep (of a sufficient duration) is important for enhancing self-control.


8) Will you be doing anything differently because of this research?

Personally, I think the study confirms what we all know from experience – and gives me an extra reason to make sure I get a good night’s sleep every night!


*Note: Correlations are used to estimate the strength of a relationship between two variables, specifically the degree to which one variable changes when another variable changes. If a correlation is zero, there is no relationship between two variables. The closer the correlation is to 1 or -1, the stronger the correlation between them. The correlation statistic used here is Pearson’s correlation. Correlations of 0.1 or 0.2 are considered weak, correlations of 0.3 to 0.6 are considered moderate, and correlations above 0.6 are considered strong.


Dr Yu Sun Bin is an epidemiologist and public health researcher. Her particular research interests are on sleep and circadian rhythms and how these biological systems are reflected in behaviour, health, and disease.