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Better Sleep Better Health

 

 

    Nobody can deny the importance of a good night sleep for one’s health. One of my friends told me that she could not sleep for days even when she was lying in bed desperately trying to sleep. She almost fell asleep when she was driving home after work one day. Another friend would wake up in the middle of the night on a regular basis and could not go back to sleep after that. Both of them felt exhausted and were not able to function during the day due to their lack of good sleep.

 

    Statistics showed that people who are chronically sleep deprived are more likely to be overweight, have strokes, cardiovascular disease, infections, and certain types of cancer than those who get enough sleep. Sleep disturbances are common among people with age-related neurological disorders such as Alzheimer’s disease and Parkinson’s disease (1).

   

    In the brain there are nerve-signaling chemicals called neurotransmitters that can regulate sleep. Gamma-aminobutyric acid (GABA) is a “calming” neurotransmitter for the brain. GABA is known to promote brain health by reducing anxiety, improving sleep, and providing an overall sense of calm. Lack of GABA can lead to depression, anxiety, and insomnia.

   

    A recent paper published in 2019 (2) reported on the effect of GABA and another relaxation factor called L-theanine (an amino acid found mostly in tea) on sleep. The study results may be of interest to those of you who would like to improve your sleep quality.

 

    Since both GABA and L-theanine were known to benefit sleep, these scientists (2) put them in GABA/L-theanine mixtures to see whether the combinations would have greater impacts on sleep than GABA or theanine alone.

 

    When they fed increasing doses of GABA to mice, the mice took less time to fall asleep and slept longer with the higher doses. The highest GABA dose of 100 mg/kg showed the most significant effect compared to the control group. This was expected as a result of GABA. Feeding 20 mg/kg of L-theanine to mice could make mice fall asleep faster (23.3%) and sleep longer (38.1%) compared to those of the control group. Among various combinations tested, the GABA/L-theanine mixture ratio of 100/20 mg/kg had the best sleep boosting effect to make mice sleep the longest time. This GABA/L-theanine (100/20 mg/kg) combination decreased the time needed to fall asleep (20.7% and 14.9%, respectively) and increased sleep duration (87.3% and 26.8%, respectively) compared to GABA (100 mg/kg) or theanine (20 mg/kg) alone. They reported that the combined use of GABA/L-theanine had synergy effects on sleep and sleep duration time (2).

   

    You may be wondering about GABA and L-theanine, especially what foods to eat to get more of them.

 

    GABA is the metabolic byproduct of plants and microorganisms. GABA is not found in fresh food, but it can be found in fermented foods. An example is kimchi (a traditional Korean dish), which is fermented cabbage that tastes both spicy and sour. Kimchi that has been fermented with lactobacillus contains GABA. Other lactobacillus-fermented foods containing GABA include kefir, miso, sauerkraut, tempeh and yogurt. For a list of fermented foods and their GABA contents, take a look at the paper by Dhakal et al (3).

 

    Among traditional fermented Chinese foods, such as furu, douchi, soy sauce, and doujiang, higher GABA contents were found in furu juice and curd with amounts of 1225.7 mg/L and 735.2 mg/kg, compared to 368 mg/kg in doujiang (4).

 

    If you drink pu-erh tea, then you may get more GABA from it than green tea. Pu-erh tea is a dark, fermented tea from China's Yunnan province. Pu-erh tea leaves contain about four times more of bioactive GABA than that of fresh green tea leaves (4.90 vs 1.27 mg/g, respectively) (5).

 

    L-theanine can be found mainly in green and black tea. It benefited patients diagnosed with anxiety by increasing levels of dopamine and GABA in the brain, and also improved test performance (6,7). The amount of L-theanine found in tea significantly increased alpha brainwave activity, which promotes relaxation without causing drowsiness, and allows a person to remain focused and alert, yet calm (8). L-theanine could also significantly lower stress markers under a stressful situation; thus, it may be useful to help combat stress (9). Not only could L-theanine be used for stress relief, it could also be used for the treatment of anxiety, improvement of concentration and focus.

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    This recent paper (2) showed the synergy effect of GABA and L-theanine as a combination for sleep. The 87.3% longer duration of sleep sounds like a lot of sleep it may induce. Even though the doses to the mice would not be the same as to the humans, the next time when you need some help to sleep try eating some furu and drinking some tea.

 

References:

  1. Brain Basics: Understanding Sleep. National Institute of Neurological Disorders and Stroke.

  2. Suhyeon Kima, Kyungae Joa, Ki-Bae Hongb , Sung Hee Hanc and Hyung Joo Suhd. GABA and l-theanine mixture decreases sleep latency and improves NREM sleep. Pharm Biol. 2019; 57(1): 65–73. 

  3. Radhika Dhakal, Vivek K. Bajpai,* and Kwang-Hyun Baek* Production of gaba (γ – Aminobutyric acid) by microorganisms: a review. Braz J Microbiol. 2012; 43(4): 1230–1241. 

  4. 史小峰,栾广忠,曹万新.  传统发酵豆制品中γ-氨基丁酸的比色测定.中国调味品. 2008(03)

  5. Jeng KC, Chen CS, Fang YP, Hou CW, Chen YS. Effect of microbial fermentation on content of statin, GABA, and polyphenols in Pu-Erh tea. J Agric Food Chem. 2007;55:8787–92.

  6. Higashiyama, A. et al. Effects of L-theanine on attention and reaction time response. Journal of Functional Foods (2011) 3, 171-178.

  7. Bryan, J. et al. Psychological effects of dietary components of tea: caffeine and L-theanine. Nutrition Reviews 66(2):82-90.

  8. Anna C Nobre , Anling Rao  and Gail N Owen.  L-theanine, a natural constituent in tea, and its effect on mental state. Asia Pac J Clin Nutr 2008;17 (S1):167-168.

  9. Unno K1, Tanida N, Ishii N, Yamamoto H, Iguchi K, Hoshino M, Takeda A, Ozawa H, Ohkubo T, Juneja LR, Yamada H. Anti-stress effect of theanine on students during pharmacy practice: positive correlation among salivary α-amylase activity, trait anxiety and subjective stress. Pharmacol Biochem Behav. 2013 Oct;111:128-35.

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