What you eat and when you eat it has an enormous effect on your body clock, your sleep and, by extension, how many years you will live.
By ‘eat’ we mean pretty much anything you take in — food, beverages, alcohol, caffeine, nicotine, medication, herbal remedies and supplements.
Each play a role in either keeping you from deep, restful sleep or nudging your body that much closer to your optimal rhythm.
One of the latest discoveries in sleep research is the link between gut health and a good night’s rest. It makes sense.
What you eat and when you eat it has an enormous effect on your body clock, your sleep and, by extension, how many years you will live
Your entire body — including your digestive system — is designed to have predictable cycles of sleep, wakefulness and eating. And by upsetting that pattern, you throw your body off-kilter, gut and all.
An out-of-rhythm life can create an out-of-rhythm gut, but an out-of-rhythm gut can also create an out-of-rhythm life.
Conversely, good gut health can lead to good sleep. So, the healthier your gut, the easier it is to nod off and stay slumbering.
Getting your gut in order is therefore the place to start when it comes to ensuring the right amount and quality of sleep.
Trillions of microorganisms, mainly bacteria, live in your gastrointestinal tract. This is called your microbiome.
Some of these bacteria are beneficial, or health-promoting, while others trigger disease and inflammation. The goal is to keep this constantly shifting balance in favour of the good guys.
Far from only digesting your food, the gut is also home to a second nervous system, which is constantly communicating with your brain and the rest of the central nervous system.
It influences hormone production, immune system function, appetite, digestion, metabolism, behaviour, mood and stress responses.
This connection is known as the microbiome-gut-brain axis. The gut is the largest endocrine organ in the body and regulates the secretion of neurotransmitters [brain chemicals] such as cortisol, tryptophan and serotonin.
It’s also central to the immune system. Seventy per cent of the cells that make up your immune system surround your gut, and your gut flora interact with these cells to help regulate your immune response.
For that reason, you mess with your microbiome at your peril — an unbalanced gut is linked to everything from bloating, trapped wind and constipation, to anxiety, depression and skin conditions such as acne and eczema.
Good gut health can lead to good sleep. So, the healthier your gut, the easier it is to nod off and stay slumbering
And it can affect your sleep. This is because your body’s master clock works in synergy with your microbiome’s clock.
If one of these rhythms is disrupted, the other goes, too. Jet lag, for example, disrupts the diversity of gut flora.
And when either the circadian rhythm [the natural cycle of your body clock] or microbiome rhythm is upset, it creates a vicious cycle. Glucose intolerance, weight gain and metabolic changes can occur — all of which affect sleep and further distort the overall rhythm of your system.
The good news is that a malfunctioning gut can be healed. Your microbiome, like your body, is designed for predictable cycles of sleep, wakefulness and eating. So as you bring yourself back into rhythm by adopting new habits, your gut will follow suit.
And one of the biggest influences on your microbiome’s health is your diet.
Think about what you are eating
Firstly, avoid sugary, starchy and processed foods. Those with lots of sugar and easily digested starch, such as pastries and processed breads, are mostly broken down in the small intestine. This can result in the proliferation of harmful bacteria, leading to bacterial overgrowth there.
Secondly, try to avoid glyphosate-sprayed crops. Glyphosate is a herbicide applied to a range of crops to kill weeds. It is also used as a drying agent before wheat and barley are harvested. Shop organic where you can, or grow your own.
The habits that are designed to keep you in rhythm and improve your overall health — exercising, cutting back on alcohol, quitting smoking — will ultimately benefit your microbiome, and your sleep, at the same time
Also, where possible, bypass the overuse of antibiotics. Sure, every so often a raging infection may warrant such treatment, but much of the time they’re unnecessary and can lead to potentially dangerous antibiotic resistance.
Inside the gut, they can be indiscriminate killers, taking out the good bacteria along with the bad. If your doctor prescribes them, ask whether alternative treatments are available.
Prebiotics are fibres in food that most of our digestive system can’t break down, but the bacteria in our microbiome certainly can.
They are like microflora superfoods, giving your ‘good’ bacteria the high-octane fuel they need to do all the things that keep your gut healthy. This includes protecting the gut wall, digesting your food, keeping the bad guys in check, contributing to your immune system and coordinating with your central nervous system.
Foods rich in prebiotic fibre include garlic, onions, radishes, leeks, asparagus, Jerusalem artichokes, broccoli, lentils and chickpeas.
Fermented foods are also good news. Sauerkraut, yoghurt, kimchi (Korean fermented cabbage), miso and kefir (fermented milk) are loaded with beneficial bacteria that join forces with the good stuff in your gut.
Research suggests that the newcomers help the long-time residents do a better job of protecting your health, so try to have a few servings every week.
Although it’s always best to get your probiotics from food, you can also enjoy the advantages of fermented foods in easy supplement form, as a capsule or powder. If you are taking an antibiotic, balance it out with a high-quality probiotic to help keep your belly on an even keel.
Remember, your gut is a microcosm of your body as a whole. The habits that are designed to keep you in rhythm and improve your overall health — exercising, cutting back on alcohol, quitting smoking — will ultimately benefit your microbiome, and your sleep, at the same time.
Get off the sugar roller coaster
In our advice on sleeping, we make it clear it is all about picking habits that work for you, and that there’s no need to adopt a monk-like existence. But when it comes to sugar, all that changes.
Today really should be when you get this sleep-sabotaging, brain-distorting, hormone-skewing, health-bombing rubbish out of your life.
Sugary foods and drinks take your hormones on a roller-coaster ride so you don’t register hunger the way you should, making you eat more — and more often — and then store those calories as fat.
It jacks up your reward hormones so you need increasingly bigger hits just to get that nice, tasty high.
Sound familiar? It should — sugar is as addictive as tobacco and alcohol. And speaking of alcohol, sugar in the form of fructose [fruit sugar] can be just as hard on your liver, which converts it into fat.
Sugary foods and drinks take your hormones on a roller-coaster ride so you don’t register hunger the way you should, making you eat more — and more often — and then store those calories as fat
When eaten repeatedly, sugar can set you up for weight gain, high blood-sugar levels, inflammation, type 2 diabetes, heart disease, cancer, dementia, depression and infertility.
A 2016 study confirmed that a higher sugar intake is also associated with lighter, less restorative sleep and more night waking. Another study from Columbia University in the U.S. concluded that a diet high in refined carbs — particularly added sugars — is linked to a risk of insomnia, especially in women aged 50-plus.
And metabolising sugar uses up lots of magnesium, which you need to support levels of GABA, a neurotransmitter that promotes sleep.
The truth is, you’re probably eating more sugar than you think. Anything that comes in a packet probably has some hidden in there, whether it’s for taste, as a cheap preservative, or just to keep you hooked.
These tend to be labelled as ‘added sugars’ and include cane sugar, high-fructose corn syrup, and ‘natural’ sweeteners such as honey, agave, maple syrup and fruit juice.
But unless a sugar is bound by fibre (as occurs naturally in fruit and vegetables), there’s no such thing as ‘healthy’ or ‘natural’.
Always check the labels before buying food products, especially condiments, snack bars and drinks, where sugar often lurks.
Why happy hour is the best time for a tipple
Studies have shown that our bodies process alcohol more effectively at certain times of the day.
It turns out they are attuned to Happy Hour, metabolising alcohol best in the early to middle hours of the evening rather than later at night. Certain types of alcohol, such as vodka and gin — without sugary mixers — may also be tolerated better.
The same applies to caffeine, so think about when you decide to drink anything containing it.
When you are feeling tired, what could be more inviting than caffeine? It gives you an almost instant second wind, laser-focuses your mind and potentially helps you burn more calories at the gym. But when it comes to sleep? Total disaster.
That is because caffeine is a stimulant — and the way it revs you up is by blocking the receptors in your brain that recognise the sleep-inducing neurotransmitter [or brain chemical] adenosine.
Adenosine is what builds up in your system during your waking hours, creating sleep pressure or the urge to sleep.
Caffeine basically stops that happening, tricking the brain into believing it’s not tired. But the longer caffeine blocks adenosine, the more it builds up in your system. When the effects of caffeine eventually wear off, all that backlogged adenosine comes rushing back into the brain, making you feel even more tired than before you had that coffee/black tea/energy drink.
Caffeine inhibits melatonin production even more than bright light does, further disrupting sleep.
So now you need caffeine to wake up and function, which makes you sleepier, which makes you need more caffeine — a circular process known as the ‘caffeine causality loop’.
If you want to aid sleep, you must catch that loop mid-stream and reset the rhythm. The way to do that is to be smarter about how much caffeine you are having and when.
Set a caffeine cut-off. We recommend having your last hit no later than 1pm.
Caffeine has a half-life of roughly five to seven hours, meaning that five to seven hours after you drink a coffee, half the caffeine is still in your body.
If you are a slow metaboliser, this could take even longer. Try cutting back on the number, or size, of coffees you drink — or have a decaf one instead of one of your normal drinks.
Meal planner for a peaceful night
In order to fully resync your sleep rhythm, you have to change your eating patterns to support your body’s digestive cycle.
Consider this your new menu for sleep:
Keep to regular mealtimes. Your body learns to anticipate feeding time, releasing enzymes and hormones to help with digestion.
Eating at the same time every day not only ensures that you’re digesting properly, but it also guarantees that the ebb and flow of your metabolism is in sync with your master clock.
In order to fully resync your sleep rhythm, you have to change your eating patterns to support your body’s digestive cycle
This goes for the weekends, too. If you change your habits for just those two days, you’re inflicting social ‘jet lag’ on your rhythm. And suffice to say that your body functions don’t observe the days of the week.
Break the fast gently. The morning is when your body is shifting back into day mode, but hasn’t fully hit its stride. Gently introduce food to your digestive system with a light, nutrient-rich breakfast.
Smoothies are a particularly great way to deliver maximum nutrition without putting a lot of stress on digestion. Another sleep-promoting option is to not eat a morning meal and follow an intermittent fasting protocol (see below).
Eat your biggest meal at noon. Your digestive system is primed to receive the majority of its fuel in the middle of the day, between 10am and 2pm.
Feed your system with a robust (ideally whole-food, veg-filled) lunch that delivers most of your daily nourishment. This will alleviate how much you feel the need to eat in the evening, when your digestive flame begins to dim.
Redefine dinner. Eating a large meal in the evening is a relatively new idea. Yes, it’s a nice time to socialise and reflect on the day, but eating a lot of food late on is not doing your digestion, or your waistline, any favours.
By the time the sun starts to set, your digestive tract is preparing for its night-time shift. So the later in the day you eat, the higher the chance that your food won’t be properly digested, leading to problems such as acid reflux, cramp and an upset digestion.
Feed your system with a robust (ideally whole-food, veg-filled) lunch that delivers most of your daily nourishment
It’s also making your digestive system work overtime, giving you less restful sleep and skewing the balance of microflora that inhabit the gut at night-time. Also, when you routinely eat your biggest meal at night, you are prompting your body to produce ghrelin, the hunger hormone, when production would normally be waning.
This ultimately trains your body to become hungry when it wouldn’t normally be and interrupts an important hormonal rhythm, while also causing your body to store abdominal fat.
So the bottom line is: eat a light evening meal, at least two to three hours before you go to bed.
Even better, go for four. But if you do eat late one night, don’t stay up trying to hit the two-hour mark. Just go to bed and start afresh the next day.
When to give your digestion a break
Brief, periodic fasts should be the norm for humans — it wasn’t exactly like we had food on demand back in the day.
And we now know that observing a longer period without eating, also known as intermittent fasting, is beneficial for a number of reasons:
- It makes your digestive system more resilient.n Your metabolism and hormones can resync their 24-hour cycle.n the metabolism is made to burn fat stored in the body.
- It allows your body to experience a longer-than-normal period of having low insulin in the blood, which tells your body to burn energy to keep insulin low (the opposite of what happens when you’re eating food continually).
- It’s a great way to gently stress your body in order to stimulate its renew and repair systems.
- It triggers autophagy, a body-wide cellular repair process that removes waste material from cells, quells inflammation, slows ageing and optimises mitochondria function, which gives you greater protection against disease.
- Work towards 16 hours between your last meal of the day and your first meal of the next. If you finish dinner at 8pm, you’ll break the fast around 12pm the following day. (Studies show that autophagy kicks in after about 16 hours.) If you need to, build up over time. Start with 12 hours (the ideal for good digestion and overnight detoxification).
- Drink water. Or, as a second-best option, tea. Third best would be black coffee. Water is ideal because anything besides it will call your liver into action and can put an end to autophagy. The counterargument is that as long as you don’t trigger an insulin response (which is what eating carbohydrates would do), then you’re still technically fasting.
- Skip all of the above if you are pregnant, nursing, on medication, an athlete doing rigorous training, underweight, or under the age of 18. Also, if you would describe yourself as extremely stressed or emotionally distraught, give it a miss — your body doesn’t need the extra burden.As always, consult your doctor if you have any concerns.