The acute effects of dried kiwifruit on sleep onset, metabolites and cognition in men

Screening visit Prospective participants will be provided with the study information sheet and invited to a Human Nutrition Research Unit (HNRU) screening session to sign the consent form and have height and weight measured, complete health questionnaires, and sleep quality questionnaires (PSQI, and ISI). Eligible participants will be enrolled. From this point on, participants will be asked to refrain from eating kiwifruit until the end of the study and maintain a sleep schedule. A case report form record (CRF) will be generated for all participants who have signed the consent form for the study, regardless of eligibility and/or continuing participation. Familiarisation Seven days before the first trial visits, participants will be invited for a familiarisation session. Participants will be asked to arrive at the HNRU between 6-8pm. The HNRU will be dimly lit to collect metabolites of interest. Once arrived, participants will be talked through exactly what would happen on a trial day with the lead researcher. They will be provided with an actigraphy watch to be used until the completion of the study and a survey booklet to be completed before the next trial visit. The survey booklet will contain a three-day food diary and a daily sleep diary. Participants will be told to activate the phase marker on the actigraphy watches when they are about to sleep and upon waking. No biomarker will be collected at his session and it is expected it will take Which will last approximately 1-2 hours. Once everything is complete, the participant will be escorted to on-site accommodation and asked to return the following morning fasted at an agreed time. Upon arriving in the morning, participants will be provided a standardised breakfast and asked to complete a cognitive test; this is used to ensure practice and learning effects are mitigated for subsequent trial visits. This morning visits will be no more than 2 hours. Intervention visits Two days before the scheduled trial visit, participants will be asked to refrain from consuming oranges, pineapples, bananas, mangos, papayas, plums, grapes, cherries, strawberries, tomatoes, capsicum, pistachios, plantains, mushrooms, chocolate, teas and coffee as these are known foods to contain and impact levels of serotonin and melatonin in urine (32-34). On the day of the trial, participants will attend HNRU between 5-6:30 pm. Participants will be asked to have their last meal five hours before the lab visit and only take water until the visit. On arrival, the participant will be asked whether they have consumed any of the restricted foods two days before or undergone exercise on this day. If the participant has consumed restricted items or exercised, the study visit will be rescheduled. If the participant has not, they will continue with the trial visit and follow the schedule below. Participants will be asked to complete a set of questionnaires (including abbreviated Profile of Mood States (POMS), International Physical Activity Questionnaire (IPAQ), Weekly Stress Inventory (WSI)) and provide a urine sample. A person trained in cannulation and venepunctures will insert a venous cannula in the arm vein of the participant to collect blood samples across multiple times points. At each blood sample, the participant's level of sleepiness will be rated according to the validated Stanford Sleepiness Scale (SSS). Approximately twenty minutes after the first blood sample, participants will be provided with a standardised evening meal [Man Size Spaghetti and Meatballs (McCain Foods), ~720 kcal], and the intervention to consume. The intervention will be in an opaque white bottle to mask what intervention the participant may be consuming. The dietary interventions will be given in random order. They will include (1) control (Flavour and colour) mixed with 200ml water, (2) control sugar (matched sugar, flavour, and colour) dissolved in 180ml water or (3) freeze-dried whole (flesh and skin) green kiwifruit (32g which is equivalent to two green kiwifruits) dissolved in 170 ml of water. Once the meal is finished, participants will be asked to sit and do light activities such as reading a book. They will also be asked not to use mobile phones or computers during their time in the lab. Six blood samples will be collected (~100mL each) beginning on arrival and 30, 60, 120, 180, 240 min post evening meal. The last blood sample will be collected at approximately 10-11 pm (differs for each participant) and the cannula will be removed after this. The participant will be asked to complete the POMS survey and provide a urine sample. They will then be provided with a urine sample collection container, saliva collection containers and survey booklet to be completed in their room the following morning. Participants will be escorted to on-site accommodation. Once settled, when the participant is ready for bed, they are asked to activate the phase marker on the actigraphy watch. Upon waking the following day, participants will be asked to activate the phase marker, collect the whole first-morning urine sample, collect four saliva samples (0, 30, 45, 60 min after waking) and complete the set of surveys. The validated surveys that will be completed in the morning are the SSS, Leeds Sleep Evaluation Questionnaire (LSEQ) and POMS. Participants will be asked to come into HNRU at the allocated time, fasted and with their urine, saliva samples and completed booklet 2-4 hours after waking. Upon arriving at the HNRU, participants will be provided with a standardised breakfast. The participant will be asked to complete a cognitive test as they did at the familiarisation session. Once they have completed this, the participant will be free to go. Participants will repeat the in-lab visit two more times separated by seven days until each intervention has been consumed.