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If you or your clients struggle to sleep well, exercise can certainly help – but, as always, nutrition also has a role to play in enhancing results. Dietitian Tara Kaff looks at what we can do to achieve more restful shuteye.




  • Eating too much or too little can affect duration and quality of sleep
  • Research has found that a high GI meal post-exercise can extend sleep duration, improve sleep efficiency and reduce the amount of time it takes to get to sleep
  • A large or fatty meal eaten close to bedtime can result in incomplete digestion, gut discomfort and disrupted sleep
  • Caffeine stays active for up to eight hours, so it’s advisable to avoid consuming it for this duration prior to bedtime
  • Increasing consumption of tryptophan – an amino acid that contributes to the production of the hormones melatonin and serotonin – can promote improved mood and better sleep.



If you feel as though you’re forever chasing that elusive eight solid hours of sleep, you’re not alone. In 2021, only around a quarter of Australians1 surveyed reported getting that much sleep each night. As a fitness professional you appreciate the role that exercise can play in encouraging better sleep, but nutrition also fits into the equation.


The following factors are worth considering if you, your clients or members regularly feel tired and lacking in energy due to insufficient or poor quality sleep.


Total daily calorie intake

The amount we eat in a day can affect our sleep. Studies have shown that if you continuously have a high calorie intake, there is an association with shorter sleep durations.


“A high calorie intake has an association with shorter sleep duration”


On the other hand, if you are in a long-term severe calorie restriction, this can also affect sleep. Studies revealed that being in too low of a calorie restriction can lead to poor sleep quality and a reduction of deep sleep.


Clearly, energy consumption is something of a balancing act. Finding that happy medium can be challenging, but it’s important to fuel correctly. It’s important to note that being in a slight calorie deficit does not have effects on sleep, the effects start to show when you are in a severe calorie restriction. Clients should, therefore, be consuming within, or only very slightly below, the recommended range for their age, gender and activity levels. This can be worked out for each individual using their BMR and PAL.


“A slight calorie deficit does not have effects on sleep, the effects start to show when you are in a severe calorie restriction”


Low GI vs. High GI carbs

Glycaemic index is a ranking system that ranks particular foods and drinks according to how quickly they raise blood sugar levels or blood glucose levels. You’re no doubt familiar with the terms ‘simple’ and ‘complex’ carbohydrates. This is a similar concept, but glycaemic index is a more intricate system than categorising foods into two simple categories.


The lower the GI, the slower the carbohydrates are absorbed, causing the blood sugar level to rise slowly in comparison to high GI carbohydrates that raise blood sugar levels a lot quicker. We should note, this system does not determine how healthy foods are: you can have healthy, nutrient dense foods that are high GI. Both low GI and high GI have a time and a place in a healthy diet.


A study completed in 2018 (Vlahoyiannis et al2) investigated the effect of glycaemic index on sleep quality and quantity. The main findings revealed that a high GI meal post-exercise extended sleep duration by 17%, improved sleep efficiency by 8.1% and reduced the amount of time it took to get to sleep by 4-fold, compared to a low GI meal after exercise.



Examples of high GI food choices can be baked potatoes, watermelon, wholewheat bread, wholewheat cereal, oatmeal and muesli. If you’re looking for a small snack pre-bed, a smoothie with oatmeal, milk and a scoop of protein powder is an example of one that would keep you fuller for longer.


Eating large meals too close to bedtime

More research needs to be done in this area, but you’ve undoubtedly heard that you shouldn’t eat large meals too close to bedtime. Why is this the case? It takes the body longer to digest a large meal; therefore, if your body is focusing on getting to sleep rather than digesting your food, your food may go undigested or partially digested. This can lead to gut discomfort which disrupts your sleep. Additionally, it is quite common for someone to get heartburn by lying down in bed straight after a big meal.


“If your body is focusing on getting to sleep rather than digesting your food, your food may go undigested or partially digested”


High fat evening meals

While large meals may negatively impact sleep, so can high fat meals. Like large meals, those high in fat take the body longer to digest, and therefore have a similar effect in terms of discomfort and interrupted sleep.


Bedtime bulking

What should you do if you are trying to achieve gains and you’re supposed to eat before bed? As a sports dietitian, I always recommend having a small snack pre-bed when trying to put on size. A small snack rich in protein will do the trick – this may even have an effect on your body’s tryptophan levels (see below for more on this). A good night time snack might be a protein shake, protein yoghurt or some cottage or ricotta cheese with berries. 


Good sleep hygiene

Sometimes, poor quality sleep has absolutely nothing to do with the food you are consuming. It could simply be a case of poor ‘sleep hygiene’, or your sleep habits. Here are a few tips and tricks to improve sleep hygiene.

  • Go to sleep and wake up at the same times every day
  • Listen to your body, and sleep when you’re actually tired
  • Keep your bedroom at a lower temperature, but be sure to keep hands and feet warm
  • Avoid screen time for at least 30 minutes before bed
  • Invest in a good mattress.



Afternoon caffeine intake

Caffeine has a life of 6-8 hours, so it is recommended to not consume any source of caffeine for this amount of time before sleep in order to reduce risk of encountering sleep problems. If you are a 10pm sleeper, for example, avoid caffeine consumption after around 2-4pm. A lot of people say “Oh, but I drink coffee in the afternoon and I get to sleep fine”. It’s not just about the time it takes you to get to sleep, however, it’s also about how it affects the quality of that sleep.


“It’s not just about the time it takes you to get to sleep if you consume caffeine – it’s also about how it affects the quality of that sleep”


Of course, having a warm drink before bed can be a soul soother, but that doesn’t mean that coffee, black tea or chocolate drinks are a good idea. There are numerous alternative options to choose from, such as decaf herbal teas like X50 SLEEPY that are formulated with a tea blend to help put you in a relaxing state and shut your eyes. Some well-known herbs that have been found to have a positive impact on sleep are valerian root, chamomile, linden flower and lavender.



Tryptophan in the diet

Tryptophan is an amino acid that is known to have an effect on our happy and sleepy hormones. It can be converted into a molecule called 5-HTP (5-hydroxytryptophan), which is used to make serotonin and melatonin. Melatonin is the hormone that essentially manages your wake-sleep cycle and serotonin can have an effect on sleep, cognition and mood. Increasing the level of tryptophan in your diet can therefore promote better sleep. Some foods that contain tryptophan include chicken, eggs, salmon, oatmeal, milk and banana.



The holy grail of eight hours of good quality, uninterrupted sleep need not be a dream. Experiment with some or all of these factors to see whether you can positively impact your sleep and, consequently, enhance your mood and energy levels.




For your chance to win 1 of 2 prize packs containing a range of herbal teas from X50 email and tell us in 50 words or less your most effective tip for a good night’s sleep.



Competition commences 14 September 2021 and concludes 2 November 2021. Competition is a game of skill and chance plays no part in determining the winner. The judge’s decision is final and no correspondence will be entered into. Winners will be selected by the editor and will be notified by email no later than 9 November 2021.Click HERE for full Terms and Conditions.







Tara Kaff, APD BNutrDiet

Tara is a Sydney-based Accredited Practising Dietitian and Sports Nutritionist specialising in sports performance-based nutrition. She is Head Sports Dietitian & Product Development Manager at healthy nutrition company X50 Lifestyle Australia. / /



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