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Research Quest on the science of gratitude, sleep and tennis

Research Quest on the science of gratitude, sleep and tennis
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1) 2018 study by Fleming et al.:​​

A few months ago, I gave genetic feedback to a tennis player on his performance DNA results.I found this paper incredibly helpful as the researchers looked at the nutrition and recovery habits of competitive tennis players from Europe and North America before, during and after their matches.

Here are some points from their findings:

• 3 – 4 hours before the match the majority of players consumed pasta, oatmeal, and sandwiches. It was important that the foods were lower in fat, protein and fibre to prevent gastrointestinal issues.

• During the match, 94% drank water, 86% ate bananas, and 50% had sports drinks.

• 77% didn’t monitor water intake; of those that did, 50% aimed to drink 500mL and 44% aimed for more than 2L of water.

• 14% reported that they had to eat more when playing on clay (I had never considered this).

• After the match, 77% foam rolled, 40% took ice baths, 37% had a protein shake and 26% took a hot bath.

​​​2) 2014 Study by Tahara & Shibata:


I’m a big fan of sleep research. I think it is the most under-utilised and under-estimated tool for health & performance improvement.​

This paper discusses Chrononutrition, which is the interaction between food and our circadian rhythm.

  • Our internal clock can be adjusted by our timing and nature of food intake.

  • Falling asleep and waking up is regulated by neurotransmitters.

  • The function of these neurotransmitters can be altered through our diet.

For example: In order to induce sleep we need melatonin. The precursor to melatonin is serotonin. Tryptophan is needed to make serotonin.

Here comes our intervention – not only can we consume tryptophan (think chicken, turkey, tofu) but our diet is going to influence the ratio of tryptophan to certain amino acids, which may either increase or decrease our ability to use it in the first place.

​​​3) 2021 study by Hazlett et al.:


While I am a big believer in gratitude (starting a daily gratitude journal was life changing for me), I wasn’t aware that there is actual documentation of the objective measures that gratitude has on one’s physical health.

This paper looked at the physiological mechanisms behind those who practiced 6 weeks of written gratitude versus a control group. After doing 5 to 10 minutes once a week of writing on being thankful, the gratitude group had reduced inflammatory cytokines such as IL6 and TNF-alpha.


1) Fleming JA, Naughton RJ, Harper LD. Investigating the Nutritional and Recovery Habits of Tennis Players. Nutrients. 2018 Apr 3;10(4):443.

2) Tahara Y, Shibata S. Chrono-biology, chrono-pharmacology, and chrono-nutrition. J Pharmacol Sci. 2014;124(3):320-35. doi: 10.1254/jphs.13r06cr. Epub 2014 Feb 27.

3) Hazlett LI, Moieni M, Irwin MR, Haltom KEB, Jevtic I, Meyer ML, Breen EC, Cole SW, Eisenberger NI. Exploring neural mechanisms of the health benefits of gratitude in women: A randomized controlled trial. Brain Behav Immun. 2021 Jul;95:444-453.

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Written by Kyle van Heerden

Online Educator at Research Raconteur

Top 10 Research Quests from Research Raconteur

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