Just two cups of tea daily can improve sleep and cut stress
A solution to the nation's poor sleeping habits and stressful lives can be found in a cup of black, green, or herbal tea infusions, according to a new study – Tea and Herbal Infusions, Psychological Stress, Anxiety & Sleep Health: A Systematic Review of Human Trials & Mechanistic Studies[1] – which analysed 33 different studies including eight human intervention trials.
The review, commissioned by the Tea Advisory Panel (TAP) (www.teaadvisorypanel.com) and authored by nutrition and well-being experts, found that sleep quality, efficiency and duration, as well as stress management, can be aided by several types of tea including regular black tea – the typical British cuppa – and green tea, German Chamomile, Lavender, Rose, Jasmine, and Passionflower.
One in four adults gets fewer than the recommended 7-9 hours of sleep nightly[2], according to studies from the UK, US, and Netherlands[3]. The worst affected are women aged 40+ years, who have the shortest sleep durations and poor sleep efficiency, while half of teenagers sleep less than the optimal 8-10 hours a night for their age group. Sleep efficiency is the ratio between trying to get to sleep and actually sleeping.
Author of the new study, and a member of TAP, Dr Tim Bond says: "Our research has found that a surprising number of different tea types can lower stress and lead to better sleep and relaxation. The herbal tea infusions are probably better known for their calming properties, but studies also confirm that green tea, oolong, and the typical British cuppa have an effect at intakes of just two cups a day.
"This adds to real world data from a survey reviewed by TAP[4] which found that nearly six in ten (57%) UK adults feel relaxed when they drink tea, and half feel calm. Similarly, four in 10 (42%) report that regular tea drinking helps with stress and anxiety and 23% say it combats low mood.
"The active compounds in tea that could help send us to the Land of Nod include polyphenols, L-theanine, theaflavins, thearubigins and gamma (γ)-aminobutyric acid (GABA). Both L-theanine, an amino acid, and GABA have direct effects on the brain, helping to activate pathways that lower stress and create calm and relaxation. Tea is the main natural source of L-theanine in our diet".
GP, Dr Gill Jenkins, warns about the health risks of getting too little high-quality sleep, commenting: "Having less than six hours of sleep a night has been found to boost levels of C-reactive protein which indicates that the body is fighting inflammation. Levels of gamma glutamyl transferase, a marker of liver damage, also rise by more than 10% after chronic poor sleep. These and other changes have serious health implications.
"Studies show that sleeping less than seven hours a night is linked with increased risk of type 2 diabetes, obesity, hypertension, depression and impaired immune function. In the short term, poor quality sleep affects cognitive and task performance, heightens feelings of fatigue, and impedes decision-making. That's why we ignore sleeping problems at our peril".
More proof that drinking tea has positive effects on stress, anxiety, mental well-being and as a result sleep comes from the studies reviewed by Tea and Herbal Infusions, Psychological Stress, Anxiety & Sleep Health: A Systematic Review of Human Trials & Mechanistic Studies. These included:
A study in young adults found that two daily cups of matcha green tea significantly lowered anxiety.
Six weeks of black (regular) tea lowered stress hormone levels and increased relaxation in a group of men asked to perform stressful mental tasks. Great news for those people looking to bust stress and sleep troubles.
Elderly adults drinking lavender tea twice daily had lower anxiety and depression levels.
Two cups of rose tea daily improved mental well-being in teenage girls.
Levels of chromogranin A – a stress response – increased in students performing mental stress load tasks.
Dr Tim Bond from TAP comments: "Stress and poor sleep can become a vicious cycle which seriously impacts on mental performance and physical health. But lifestyle changes including tea drinking and sleep hygiene can make a difference.
"As our new review provides good evidence that even two cups of tea daily can aid sleep quality, relaxation and bust stress due to the high concentrations of L-theanine and polyphenol compounds. Several types are effective including the well-loved British cuppa, green tea, and herbal tea varieties, particularly German Chamomile, Lavender, Rose, Jasmine, and Passionflower.
"Incorporating two cups of tea into our evening routines could make the difference between tossing and turning and getting some serious shut eye".
