The study will test whether the consumption of a low versus a high glycemic index pre-bed drink influences sleep architecture, memory consolidation, nocturnal glucose metabolism, and mood.
Few studies have examined the impact of meal composition on sleep. Most research has focused on carbohydrate intake, although reports are sporadic and confounded by the manipulation of other macronutrients. Nonetheless, the pattern of results appears to depend on the nature of the sleep variable under investigation e.g., latency, duration, or efficiency. The study will determine whether manipulating the glycemic index of a pre-bed drink influences sleep architecture, procedural and declarative memory consolidation, nocturnal glucose metabolism, and mood. Participants will stay in the sleep laboratory for three nights, each night separated by one week (visit 1, 2, and 3). The first night is an acclimatisation night. The same procedure will be followed on all three nights, as described below. On the morning of each visit, a continuous glucose monitor will be set up and worn until 8pm the following evening. Participants will be asked to return to the sleep laboratory at 7pm, having fasted for five hours, and asked to consume a standardised evening meal. Several mood questionnaires will be completed throughout the evening and a polysomnography will be set up. Two memory tasks will be administered at approximately 10pm. Immediately after this, participants will consume either water (night 1), or a low glycemic index or high glycemic index drink (night 2 or 3). Participants will retire to bed at approximately 11pm and woken up between 6.30am - 8am, depending on personal preference. In the morning, the memory tasks will be administered again, as well as two mood questionnaires. Participants will be asked to wear a Pro-Diary watch throughout the day, which measures mood and hunger. At 8pm, both the continuous glucose monitor and Pro-diary watch will be collected from the participant.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
OTHER
Masking
TRIPLE
Enrollment
20
Fruit flavoured drink with low glycemic index sugar (300 ml)
Fruit flavoured drink with high glycemic index sugar (300 ml)
Swansea University
Swansea, West Glamorgan, United Kingdom
Sleep onset latency (polysomnography)
Onset of sleep from the time the lights are turned off.
Time frame: Bedtime (approx. 11.00pm) to wake time (approx 7.30am)
Total sleep time (polysomnography)
The total number of hours of sleep.
Time frame: Bedtime (approx. 11.00pm) to wake time (approx 7.30am)
Wake after sleep onset (polysomnography)
Hours of wake time after three epochs of sleep have occurred.
Time frame: Bedtime (approx. 11.00pm) to wake time (approx 7.30am)
Sleep efficiency (polysomnography)
Total sleep time divided by the time from lights out until awakening in the morning.
Time frame: Bedtime (approx. 11.00pm) to wake time (approx 7.30am)
Sleep stages (polysomnography)
Time spent in each sleep stage.
Time frame: Bedtime (approx. 11.00pm) to wake time (approx 7.30am)
Arousal index (polysomnography)
Number of arousals throughout the night.
Time frame: Bedtime (approx. 11.00pm) to wake time (approx 7.30am)
Leeds Sleep Evaluation Questionnaire
Subjective assessment of sleep quality. Scores range from 0 to 30. Higher scores indicate poorer sleep quality.
Time frame: Administered 10 - 20 minutes after waking up in the morning,
Glucose response (continuous glucose monitor)
This platform is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional.
The 2h and 3h incremental area under the curve (iAUC) will be used to assess glycemic response to the pre-bed drink. The mean amplitude of glycemic excursion (MAGE) will be assessed as an indicator for glycemic variability during the night and for 25 hours.
Time frame: 25 hours during night 2 and night 3 (weeks 2 and 3)
Finger tapping task (procedural memory)
The change in performance from the learning phase to the recall phase.
Time frame: Completed at 10pm, and between 6.30 - 8am the following morning, on night 2 and night 3 (week 2 and 3).
Story recall task (declarative memory)
The number of content words (nouns, adjectives, and verbs) correctly recalled.
Time frame: Completed at 10pm, and between 6.30 - 8am the following morning, on night 2 and night 3 (week 2 and 3).
Epworth Sleepiness Scale
Subjective assessment of daytime sleepiness. Scores range from 0 - 24. Higher scores indicate more daytime sleepiness.
Time frame: Administered at 8pm on the evening after night 2 and night 3 (week 2 and 3).
Mood and hunger
Scores range from 0 - 100. Higher scores indicate stronger feelings.
Time frame: Completed five times throughout the evening and twice in the morning (immediately after waking up and 20-30 minutes later) on night 2 and night 3 (week 2 and 3). .
Mood
Pro-diary watch
Time frame: Prompted from 9.30am - 5.30pm after night 2 and night 3 (week 2 and 3).
Actigraphy
Time spent in each sleep stage.
Time frame: Night 2 and night 3 (week 2 and 3).