The effect of green tea amino acid L-Theanine formulation on markers of stress and quality of sleep (THESLeep Project)

INTERVENTION: All enrolled participants will be allocated into one of the three treatment groups or into the control group. After one week baseline measurements, participants in the treatment groups will be provided with the L‐theanine sachet for period of two weeks containing, flavoring and effervescent powder and 100, 200 or 400mg of L‐theanine. Participants will be asked to consume the content of the sachet by dissolving it in the water (around 125 ml) one hour before bedtime every evening for 14 days. Participants will be asked to return their supplement at the end of the treatment period. Unused sachets will be counted to determine the compliance. CONDITION: Alternative and Complementary Medicine ‐ Other alternative and complementary medicine Mental Health ‐ Anxiety Neurological ‐ Other neurological disorders Quality of sleep;Anxiety; ; Quality of sleep ; Anxiety PRIMARY OUTCOME: Pittsburgh Sleep Quality Index (PSQI)[Administered at screening, baseline (Week 1 post‐screening), start of the treatment (Week 2 post‐screening), end of the treatment (Week 3 post‐screening) and two week post completion follow up.] Sleep onset latency (Measured using Motionwatch 8 Actigraphy device)[Administered every night during the baseline period (Week 1 post‐screening) and during the treatment period (Week 2 and 3 post‐screening)] The Consensus Sleep Diary (15 item)[Administered every night during the baseline period (Week 1 post‐screening) and during the treatment period (Week 2 and 3 post‐screening)] SECONDARY OUTCOME: Depression Anxiety and Stress Scale 21 (DASS‐21) ‐ this will be assessed as a composite outcome[End of baseline week (Week 1 post‐screening) and End of treatment period (Week 3 post‐screening)] Heart Rate Variability (using Polar H10, HR Sensor chest strap)[End of baseline week (Week 1 post‐screening) and End of treatment period (Week 3 post‐screening] Percent sleep efficiency (Measured using Motionwatch 8 Actigraphy device) ‐ This is an additional primary outcome[Administered every night during the baseline period (Week 1 post‐screening) and during the treatment period (Week 2 and 3 post‐screening)] Resting Blood Pressure using digital blood pressure monitor (Omron, Florida, USA)[End of baseline week (Week 1 post‐screening) and End of treatment period (Week 3 post‐screening)] Salivary marker of stress (alpha‐amylase)[End of baseline week (Week 1 post‐screening) and End of treatment period (Week 3 post‐screening) ] Salivary marker of stress (diurnal cortisol)[End of baseline week (Week 1 post‐screening) and End of treatment period (Week 3 post‐screening)] Sleep duration (Measured using Motionwatch 8 Actigraphy device) ‐ This is an additional primary outcome[Administered every night during the baseline period (Week 1 post‐screening) and during the treatment period (Week 2 and 3 post‐screening)] Total sleep time (Measured using Motionwatch 8 Actigraphy device) ‐ This is an additional primary outcome[Administered every night during the baseline period (Week 1 post‐screening) and during the treatment period (Week 2 and 3 post‐screening)] Wake after sleep onset (Measured using Motionwatch 8 Actigraphy device) ‐ This is an additional primary outcome[Administered every night during the baseline period (Week 1 post‐screening) and during the treatment period (Week 2 and 3 post‐screening)] INCLUSION CRITERIA: Healthy participants with mild to moderate sleep disturbances that score greater or equal to 5 on the Pittsburgh Sleep Quality Inde X(PSQI) questionnaire.