YOU COULD TRY

✢ THE DRINK Slow

Cow, £17.99 for 12, Amazon. A sparkling water infused with six ‘relaxing’ plant extracts, including L-theanine.

✢ THE DAY HELP Solgar L-theanine 150mg

Free Form, £29.99, hollandandbarrett.com. Best taken twice a day. ✢ THE NIGHT NURSE New Nordic Melissa Dream, £14.95, newnordic.co.uk. With lemon balm extract and 134mg L-theanine.

✢ THE SACHETS Pink Cloud Relax Drinkable Vitamins, £24.99, hollandandbarrett.com. Taken hot or cold, these hold 50mg L-theanine.

✢ THE TEA FOGA Focus Matcha Latte Blend, from £11.50, foga.co. Dr Newman-beinart says: ‘Matcha is the best way to get the most out of L-theanine. Rather than soaking tea leaves, then removing them, it’s made by grinding them into a powder.’