Dr Rupy: Hello and welcome back to the Doctor's Kitchen podcast. Today we're going to be talking about principle five, eat in time. I've invited consultant paediatrician Dr Michael Farker from Evelina London Children's Hospital who has a specialism in sleep medicine to discuss the mechanisms of what eating at different times can have on sleep function and therefore health. I also go on to talk about fasting diets available, different things like intermittent fasting, 5:2 diets and the evidence behind them. So first of all, do you mind telling us about your background and what actually sparked your interest in sleep medicine?
Dr Michael Farker: So I'm a paediatrician. I've worked with kids for 17 years or so. My interest in sleep started actually because I had a sleep difficulty when I was a teenager, so I had something called sleep paralysis, which is this quite frightening experience that you sometimes get where you wake up and you are partly awake, partly asleep, but you feel like you can't move. And at the time the doctor that I went to to tell about this didn't really know very much about it and I went and researched it and it sparked an interest in sleep which I've then kind of tracked all the way through my career and ended up where I'm doing that just now.
Dr Rupy: And so what are your current goals with sleep medicine right now? You're doing a lot of work around this subject obviously as part of your clinical work.
Dr Michael Farker: So my day job is I'm a consultant in paediatric sleep medicine. So we are there to support children with sleep difficulties, usually children who have either very complex or refractory sleep difficulties, often in the context of other illnesses. So we look after lots of children who have conditions such as autism or ADHD where sleep problems can be a very big part of the presentation and can really impact the family as a whole. And we also have responsibility to those children who have the more unusual, so sleep diseases are relatively rare, but illnesses like narcolepsy for example are more common than I think many people realise and can often be unrecognised. So we're there to help with the assessment and management of the complex, rare, refractory sleep difficulties. What we're not there for unfortunately is to help every family get their toddler to magically sleep through the night. And one of the interesting things about sleep, while there are broad principles that apply pretty much universally, everybody is very different. So there isn't a one size fits all necessarily for everybody. So thinking about your body clock for example, most people know if they're a morning person or an evening person, a lark or an owl. And that is genetic. So whether you are ready to get up and go first thing in the morning and then you're probably going to want to go to bed quite early in the evening. Or you're somebody who functions at your best in the late hours of the night but then you really don't want to get up in the morning is genetic.
Dr Rupy: So that's the genetic, that's the predisposition.
Dr Michael Farker: That's all to do with how your body clock is set. And depending on how your body clock is set, then different strategies if you have sleep problems might be appropriate for you. So it's general principles are very valid, but there is a lot of individual variation that you need to think about when trying to help people with sleep difficulties.
Dr Rupy: Absolutely, yeah. That's fascinating. And what actually happens when we sleep? I know this is a million dollar question, but what what actually happens?
Dr Michael Farker: So one of the fascinating things about sleep is that we haven't really been able to explore what goes on when we sleep in great detail until relatively recently. So the last 50 to 100 years or so, we've been able to start thinking about what happens when we sleep. When you sleep, what you are doing is you're reducing your awareness of the world around you and there's a lot of functions that go on when we sleep which our body and brain depends on. So sleep is something that you spend, so over the course of your whole lifetime, you're going to spend about a third of your life asleep. From an evolutionary perspective, we don't tend to value things like that unless there is a benefit to them. So you're spending a third of your life doing this, there must be lots of good reason why that's the case. And we are constantly discovering new things that sleep is implicated in. You may have seen in the last week or so the Nobel Prize for medicine and physiology was awarded for researchers who have done a lot of work in the body clock. And one of the things that we're understanding is that the function of our body is quite tightly tied to our body clock. So our body clock tells us we should be awake in the daytime and asleep at nighttime. When we function against our body clock, our bodies don't work the way they should do and that has consequences. But sleep does lots of things. So it's important in children for growth and development, both physical and mental. It's important for consolidating learning, it's important for emotional regulation, it's important for the function of every body system you've got. So if you are mildly chronically sleep deprived, your immune system doesn't function as well as it would do. So you're more likely to get trivial colds. Anything that you can pick, I can probably find a way to tell you that sleep is important to it functioning as well as it should do.
Dr Rupy: Absolutely, yeah. So given that we now established sleep is very important, how does eating positively or negatively impact your sleep?
Dr Michael Farker: So sleep and eating, appetite, hunger have quite a complex relationship and it's one that we're increasingly, again, it's an area that we're rapidly increasing our understanding of. On a very basic level, sleep is something that depends on good routines and habits. So that body clock that keeps you awake in the daytime, asleep at nighttime. For most people, your body clock is not set to 24 hours. So most people's body clocks run slightly longer, slightly shorter than 24 hours. So you're constantly resetting your body clock. And we do that through regular routine and cue. So the most important of those is light. So exposure to daytime light and as much good quality natural light as you can in the daytime and then darkness at nighttime helps to keep your body clock in tune. That's why we, you will see people like me harping on quite a lot about the negative impact of electronic devices at bedtime on sleep quality because they really affect the timing of the body clock.
Dr Rupy: That's something that's never been more appropriate to talk about, right? In this era of hyperconnectivity and social media.
Dr Michael Farker: You know, so the iPhone is only 10 years old. So it's not really been around for very long, but now if you say to people, I'd like you to go without your iPhone for a day, they just go, oh, there's no way I can do that. We've become very, they've become very integrated into our lives very quickly. And that has, there's a lot of very positive benefits to them, they're brilliant, but particularly for sleep, they are not good and they are contributing to a significant increase in sleep problems and sleep quality, I think, that we're seeing both in children and in adults. So light is the most important of those cues, but lots of other things help regulate it. And the more consistent your routine is, the stronger the reinforcement of your wake and sleep rhythm, if you like. And eating is also a very, very powerful social cue. So the more regular your routine is with eating, so breakfast, lunch, dinner, consistent times, helps to reinforce wake, and then that also then helps to support the sleep side of things. The better your routine in the daytime, the better the sleep rhythm is reinforced. So one of the difficulties, for example, around about people who may not have as good eating routines. So if you're somebody who doesn't have regular meal times, you graze, particularly if you then snack and graze late into the evening into the night, you lose some of that reinforcement of the natural wake sleep rhythm. The other way around though, and again, this is something that we're again, increasingly understanding is that when we are sleep deprived, and probably being honest, most adults in this country are probably sleep deprived by about an hour per week on average, which doesn't sound very much and most of us are, you know, taking another coffee and cope. But an adult should get about seven to eight hours of sleep per night. So if you're missing an hour of sleep every night, you are missing an entire night's sleep over the course of a week. And that begins to have consequences. One of the things that changes when you are sleep deprived is the hormones which help to regulate our appetite and hunger. So leptin and ghrelin, they change when we are sleep deprived to make us more hungry, and they also tend to make us crave the foods that we know are less healthy for us, the ones that are going to give us immediate energy, immediate food rush, you know, benefit. So if you are sleep deprived, you are more likely to eat more and you're more likely to eat unhealthily. So sleep deprivation is probably a significant factor which historically we've not been aware of that is contributing to the increasing problem that we're seeing with obesity. So helping people to improve their sleep routines, their sleep habits, to learn to prioritize sleep in their lives and why, might be one of the strategies that will help us deal with obesity as a problem which we are struggling to deal with. I do quite a lot of work with people who work around the clock. So about 3 million people in this country work in jobs where they have to work at night. And what that means is they have to work against their body clock. So your brain is evolved for you to be asleep at night. It's not evolved for you to be awake and functioning and doing anything much else at all at night time. And that has consequences. And when we start to think about eating, we are increasingly realizing, so if you work night shifts regularly, your risk of obesity increases, your risk of cardiovascular disease increases, your risk of type two diabetes increases. And some of that is mediated through people's eating habits at nighttime. You are not expecting to be eating at nighttime. So normally go to bed 10 o'clock, 11 o'clock at night, wake up at 7 o'clock. We have a natural fast overnight. So the body is not expecting to be eating. If you then give a calorie load in the middle of the night when your body clock is telling you it's not expecting that, your gut is in night mode, it's calmed down, and then you ask it to start to do work, then it doesn't handle that as well. So glucose tolerance, for example, is impaired when we eat at night. And over the long course of time, that then adds into those risk factors for the other problems.
Dr Rupy: Absolutely, yeah.
Dr Michael Farker: The difficulty is that if you work at night, as I'm sure you remember from when you do, you feel that the world is against you and it's deeply unfair that it's 3 o'clock in the morning and you are having to do things and everybody else is peacefully home in bed. So we think we deserve things like chocolate and cakes and all the treats. And at the same time, again, it comes back to that hormonal effect. So because you're working at night, because you're probably chronically sleep deprived in association with working nights, you're hungrier and you're craving those foods. So it begins to get into quite a vicious circle in doing it. So one of the, when I work and talk to people about this, the least popular bit of advice I give them, which is on a par with your iPhone needs to go away an hour before you go to bed, is you need to try and think about what you eat at night. And I'm afraid that night shift calories not only count, but they actually count more than they would do in the daytime. So nighttime, night shift, cake, chocolate, all the rest of it is something I try and encourage against. And that ties in very much to that kind of idea of eating in time that you know, that we need to think about what our body is expecting and food is a very important part of what we're doing in terms of regulating that.
Dr Rupy: The simple concept of sleep deprivation being related to obesity and the feelings of what you feel that you need to eat, those cravings of sugary sort of morsels of food to to satisfy this hunger. I think a lot of people can relate to that. Particularly like 10, 11 a.m. I know when I'm in clinic, I'm just grabbing something. And if I've had a bad sleep, then yes, like the temptation to have caffeine and the temptation to have that biscuit that that lovely patient has brought in for the rest of the surgery is there.
Dr Michael Farker: And I think the one of the things I love about sleep is it's a really complicated interaction between the physiology and the psychology. So I think, you know, if you've had a rough night and you've got, you know, a busy clinic and you feel you deserve the treat on a psychological level, but there is a very definite physiological impact that has on. That's the bit I think people don't realize. It's those cravings are being driven in part by the sleep deprivation and managing sleep better can help people manage that better. So when you look at good, you know, weight loss plans, I think a lot of them do focus on more than just what to eat. They focus on the whole lifestyle. And it's about encouraging good habits across the board. So, you know, good sleep is important, regular exercise is important, healthy eating is important, routine is important. And all of these things together probably then help to significantly improve your chances of getting rid of the extra pounds and calories that you're carrying quicker and better.
Dr Rupy: Yeah, and just generally living a healthier lifestyle is going to prevent yourself from getting things like diabetes, cardiovascular problems and cancer as well that is rising in Western countries. So there's lots of explanations as to how sleep can be impacting that. We touched very briefly on hormones. Does it affect those hormones and what what sort of hormones are we talking about?
Dr Michael Farker: So from an appetite point of view, it's leptin and ghrelin, the ones who help regulate appetite and hunger. And I said the main difference is it shifts you towards being hungrier and craving foods that give you more immediate satisfaction, which tend to be the less healthy foods. Sleep is on one level a very complex physiological process with lots of things going on, but actually a lot of the time it can be boiled down to relatively simple concepts when we're thinking about it.
Dr Rupy: Okay. And I know this is going to come up in listeners' heads. So what is the ideal number of hours for sleep in terms of the the most perfect restorative sleep. I'm I'm I'm pretty sure I know the answer you're going to give, but I'm going to ask nonetheless.
Dr Michael Farker: So the answer is it's different for everyone. The average is probably for an adult around about seven to eight hours, but the range of normal can be quite wide. So I spend a lot of time looking after teenagers, for example. So teenagers need a little bit more sleep. So the median amount of sleep that a teenager needs is probably around about nine and a quarter, nine and a half hours of sleep per night. But that is a normal distribution curve. So there are some teenagers who have a normal amount of sleep who will need less sleep than that. So we'll need only seven or eight hours of sleep. But equally, there are teenagers who are perfectly normal who need 10 or 11 hours of sleep. And in our society, getting 10 or 11 hours of sleep is quite challenging. So if you are somebody who is genetically wired to need a little bit more sleep, you are going to struggle to fit that in when particularly when we don't prioritize sleep in general. Simplest, easiest way to know how much sleep you need is if you go on holiday for a week or two and you have nothing constraining your sleep. So you can get to sleep at a consistent time every night and just wake up naturally. The first few days, you will probably sleep a bit more because you'll be catching up the chronic sleep deprivation that you're almost certainly dealing with most of the time. But towards the end of the holiday, you will probably settle into a rhythm where you will go to sleep at a consistent time and you'll wake up at a consistent time. And I'll be willing to bet that that time for most people will be later than the time they would normally wake up on a work day. And that tells you that's probably how much sleep you need. So if you go on holiday at the end of the holiday, you go to sleep at 11 o'clock and you wake up at 7 o'clock, then you probably need eight hours of sleep. If you are somebody who most nights is going to bed at 11 o'clock on a work day, but you have to get up at half six to get to work, then you're missing an hour and a half of sleep every night and that has an impact. So that's that's the most useful way. But the typical figure that we quote is seven to eight hours. The average adult in this country, the last time it was looked at in any great depth is probably getting about 6.8 hours of sleep on average. So most adults are mildly chronically sleep deprived.
Dr Rupy: So I'm going to talk a little bit more about chronobiology now and that's really the impact of what you eat and how that affects your circadian rhythm, your body clock. So first of all, fasting is something that is very popular these days. What is actually a fast? So it's willing abstinence from food for a defined period of time and this can be extremely variable from 24 hours or from sunrise to sunset. Sometimes it can be days at a time and depending on the reasons as to why we fast. So the ritual of fasting is seen across multiple different cultures and religions from Islamic and Christian worlds to Asian continent where there always seems to be a festival personally in my household being from an Indian background. There's lots of reasons to fast. And for many people across the world from different faiths, fasting is actually a part of life rather than for health. But in recent times, it seems to have come into the realm of fasting being healthy for you. There's so many different types of fasting that are very popular for health reasons. So excluding religious and cultural reasons, intermittent fasting is usually the abstinence of food for over 12 hours at a time. For example, 16 hours where you do not eat to eight hours where you do. There's also time restricted feeding. So that's like a lighter version of intermittent fasting, which are two strictly different things when you look at the literature. There's also the 5:2 diet where you eat your normal calorie intake for five days and then the two days that you fast essentially are very restricted number of calories. This isn't necessarily the abstinence of food for two days, it's just less calories. And obviously there's more longer extreme version of fast. And something that's come into a lot of people's attention very recently is fasting mimicking diets that was pioneered by Professor Walter Longo and Dr. Panda. And that's catching the attention of a lot of researchers in the field of nutrition, looking particularly at weight loss, but also brain development and cancer and even dementia as well. Essentially, it's five days of low calorie, nutrient dense meals followed by 25 days of normal eating in monthly cycles. So it's important to realize that there are multiple types. Dr. Mike, it'd be really interesting to get your opinion on whether you think that we are meant to fast from an evolutionary point of view given what we know about sleep medicine.
Dr Michael Farker: So I tend to be fairly straightforward about this. I'm not a nutritionist expert. We know from our point of view that eating and eating patterns helps to regulate sleep, but we very much try and encourage healthy balanced diet in a regular routine. So breakfast, lunch, dinner, sensible snacking and an overall healthy balanced diet. My practice is with children and for that reason actually we tend to stay away from the fasting diets because even where they are appropriate and safe in adults, they are usually less appropriate for children where the priority has to be on them having a balanced diet to support growth safely. So for example, the the intermittent fasting diet that you mentioned there, the mimicking one is one that adults with narcolepsy, so narcolepsy is a primary sleep disorder, but there are certainly some adults who have used those types of diet and think it then benefits their management of their narcolepsy. The difficulty is is that they're not usually appropriate for children. So it's not something that we usually then come to directly. I think it's an interesting area. It's one that I suspect I will learn an awful lot more about over the next few years because as you say, it's there's a lot of research interest in it and there's always, and again, I think this is where it will come from our perspective is that you know, that people are always keen to find ways to treat conditions without necessarily using medicines if they can avoid it.
Dr Rupy: And it's really important to remember that these are like very, very preliminary studies that we're talking about. But it's interesting that you mentioned narcolepsy because there are some studies to show that fasting does increase certain neurotrophic factors that can improve attentiveness, concentration, which is why people are looking at it as a potential way of treating or even managing dementia as well as the multitude of other potential effects it can have on brain health in general. Whether fasting can actually affect diabetes, dementia and cancer on a population level is still to be said. There was a really interesting diabetes study that came out of a group from Newcastle. Did you come across that at all? They gave them a low calorie diet, I think for a prolonged period of time and reversed diabetes in 100% of the cohort and maintained that diabetes reversal three months after despite going back to a normal diet in most of the participants, but still again, that's a very, very small sample. So
Dr Michael Farker: The challenge, I think with both nutrition and sleep is actually just getting the basic message out. First of all, I would be happier I think if everybody knew the basics about sleep and prioritize sleep and were able to maintain a good healthy balanced diet as a first principle. And then I think there may well be rule for modifications on top of that in specific cases, but I suspect without knowing the adult data, but I suspect that if people with type two diabetes maintain a general healthy balanced diet that their diabetes will be managed better as well.
Dr Rupy: Absolutely. And you know what? I'm quite happy to get into discussing with anyone who looks after. So any specialist, I'm happy to talk to them about how sleep can help their patients. And actually, so there is good evidence that improving sleep. So if you have type one diabetes, for example, and your sleep quality is not as good as it should be, if you're chronically sleep deprived, then measures of your diabetic control are likely to be worse. So one of the ways to help improve control of diabetes may very well be to help focus on sleep quality. And again, one of the other things with sleep is it always has quite a complex relationship. So while sleep quality may affect diabetic control, poor diabetic control is likely to affect sleep quality. So we see that with illnesses like epilepsy, for example. So if somebody has epilepsy and they are sleep deprived, they are more likely to have a seizure. So somebody with a stable diagnosis of epilepsy who's been on holiday and comes back is jet lagged, sleep deprived, is more vulnerable to seizures. But equally, if their epilepsy is not well managed, then they will are more likely to have poorer sleep as a consequence of that. So the the key message with that is that almost every system in your body is affected by sleep and in particular by that body clock. So the reason that the work this month that's been awarded the Nobel Prize on the body clock merits the Nobel Prize is because of how fundamental that body clock is to our function and that's the bit that we're really beginning to unpick. So the obvious example of a hormone that is affected by sleep is melatonin. So melatonin is the hormone that in humans is supporting sleep onset particular. So it's zero at this time of the day. We start to produce melatonin in the evening, peaks around about midnight, decreases back down. We see an opposite pattern with cortisol. So cortisol tends to peak just before we're due to wake up in the morning and then drops off again. So there are lots of hormones that are tied into the body clock. And the more we understand about that, the more we realize that getting the body clock right, the sleep bit right, the better everything else is likely to function. But a lot of that work is still at a relatively early stage.
Dr Rupy: I think it's almost exemplified by your work with night shift workers and what we see with night shift workers having shorter lifespans that almost constant 24-hour access to food and this notion that we need to never be hungry and always satisfy the demand of being hungry with food, even if it is 11:00 p.m. at night and you've eaten three or four meals that day, that could be contributing to chronic lifestyle disease.
Dr Michael Farker: So I think, you know, the the idea of a physiological fast, so we are meant to fast during sleep. And if we don't, then the function is impaired. So yeah, I think the the idea of the 24/7 lifestyle. So it intrigued me, there was an exhibition across the city last month that Sadiq Khan, so London now has a night czar, whose job is to effectively, as far as I can see, to monetize the function of London at nighttime because what a waste of the economy by having everybody asleep at night. So it's all about, you know, let's get this going on at night and we can have more markets here and do this and we can have London working 24 hours a day, seven days a week. And it sounds great, but it completely ignores the fact that we are not evolved to be a 24-hour a day active organism. We are evolved to be asleep at night. Sleep is fundamental to our health. And when you start working against that, there are consequences. So yeah, this this idea of the 24/7 society sounds great on one level and I'm sure at the bottom line, Mr. Khan gets his, you know, tick off increased revenue for London, but the consequence will not be insignificant. The health of the people who do that is going to be impaired and unless that's thought about as part of that, the hidden consequences, I suspect of doing these things.
Dr Rupy: Well, you heard it here first, we need to balance the effects on the NHS versus what we invest in in terms of nighttime activities. So, looking at fasting again, just talking about as a general term, fasting responsibly and the things to look out for if you do, and I always recommend that you speak to a practitioner, a nutritionist, if you do try and partake in this, are symptoms if you're not doing well. So that can be abdominal pain, dizziness, faint, low sugar effects, and also the stress as well. A lot of people look at intermittent fasting or these sorts of diets and just think that it's going to improve their hormone levels. But actually, if you're stressed about not putting food into your body in the attempt at trying to improve your health outcomes, then it can actually have negative effects. So going back to the night shift worker, if they were really trying to not eat overnight, is there anything that you'd suggest that they would eat overnight?
Dr Michael Farker: Strictly speaking, the evidence is increasingly suggesting that we just should not eat at nighttime. So particularly, so within the NHS, most people are working runs of nights that are shorter than they used to be. So they tend to be three or four nights. And trying to maintain roughly your normal eating habits. So you're eating still predominantly in the daytime and not eating at night is probably the best way to do it. Most people find that challenging. Partly because again, it's that psychology of I just deserve something. And partly because it's, you know, if you're working at night, then you do need that boost to get you through. As much as possible, I encourage people to try and avoid eating between midnight and 6 o'clock because that's really the time when your body is very much expecting to be not handling calories and food input. And if you do snack, it's all the boring stuff. Eat healthy, straightforward foods that are ideally things that are readily preparable and take away. So I'm a great fan of soups on night shift, for example, you can, you know, batch them up and take them in and it's not a great problem to do it that way. But healthy snacks to get you through the night.
Dr Rupy: There's a lot of information there. We've learned a lot about sleep and fasting in general. I'm going to just wrap up with the Doctor's Kitchen recommendations of principles of eating on time. Generally, the safest conclusion is to avoid late night eating if you can. As a rule of thumb, it's two to three hours before bed. Spiking your sugar levels before sleeping can be detrimental to the hormones that govern sleep, as well as the other restorative mechanisms that are designed to occur during shut eye. It can affect a hormone called cortisol and another one called melatonin that we just heard about that can have many knock-on effects. Trying to keep to regular eating times, again that we've just heard from Dr. Mike Farker. This can be tricky if you're like me and you do odd hours and shift work, but eating regular patterns has been shown to be beneficial without actual change in calorie or macronutrient content as well. Please, please, please, if you do try fasting, do not fast on medications without the supervision of your practitioner, particularly diabetic medications that can be lethal. Always discuss fasting with your practitioner. And remember that fasting mimicking diets and 5:2 diets and intermittent fasting are all supported by small scale research. In fact, I think fasting mimicking diets only had their first human trials this year in 2017. So although it's really interesting and certainly from a scientist point of view and my interest point of view, it's absolutely fascinating, but we are nowhere near enough rigorous research to generalize to everyone. We are all unique. Prolonged fasting, again, not advisable without supervision or not advisable at all in my opinion. And remember that these are general guides, these are not rules. There is a lot more to a healthy lifestyle and mindset rather than just restricting yourself when you can eat is really, really part of the healthy lifestyle process as well. And this is something very important that I must mention. If you're fearful of weight or you feel that you may have tendencies to overly think the health benefits of food, fasting practices are not advisable. And I would certainly speak to a doctor and nutritionist who are trained to recognize any issues that you might have. I'm talking to young men as well as young women as well. A lot of men, particularly across social media, have these issues. A colleague of mine is actually a specialist interest in this, does a podcast called Don't Sort My Game, and that is of course Dr. Lauren Thomas, who has a PhD, and she discusses this topic regularly. I'd definitely go check it out. Is there anything else that you'd like to add, Michael? We've talked a lot here.
Dr Michael Farker: So I think I completely agree with you by the way that, you know, rigid application to routine all the time is usually counterproductive. But it's why having a good core routine is the key. So then you can have the occasional differences and without it being too much of a problem. Simple message, I think if everybody could have a bit of an idea of how much sleep they actually need to get and then try and prioritize that, I think they will likely to find that that has lots of benefits. And it may be for the people who are trying to think about weight and healthy eating that it might actually help them to control weight, lose weight by thinking about sleep as part of that equation. But as I say, it's a balanced healthy lifestyle is is the solution. No one bit is going to have all the answers.
Dr Rupy: Absolutely, yeah. There's so many different layers of complexity to healthy living. So you heard it here, eat on time and sleep your way to health. You can find Dr. Michael at Dr. Mike Farker on Twitter. I've put the link down below and on the website, the Evelina London Sleep Medicine Department. There's lots of information there and a link to the NHS shift workers sleep site that I've put the link down below as well.
