Measuring the Cardio-metabolic Response to Diet Quality Modification During Night Work.

The aim of this pilot study is to investigate the acute impact of diet quality modification during night work on 24-hr glucose variability (GV) and heart rate variability (HRV) in healthy free-living employees.

An increasing body of data reports deterioration of cardio-metabolic health in shift workers. For example, large scale meta-analyses have reported shift workers to be at increased risk of developing type 2 diabetes and of experiencing a coronary event, compared to day working employees.

Shift work causes complex changes in physiology (desynchrony of circadian rhythms) and behaviors including activity, sleep and eating patterns. The importance of meal timing is becoming increasingly recognized in both chronobiology and nutrition fields, with emerging awareness of 'chrono-nutrition', the interaction between nutrition and circadian time.

Given the importance to the economy of a healthy aging workforce, and the increase in shift work prevalence, it is important to establish if diet modification can reduce the health disparities between shift and day working employees.

Eligibility Criteria:
Inclusion Criteria:

* Current night shift worker (defined as a period of work between 11pm and 6am) working regular blocks of 3 night shifts.
* Body mass index between 18.5 and 35 kg/m2.
* Weight stable (no weight change by more than 3 kg in the last 2 months).
* Not a regular smoker (1 or more cigarettes per day) and would be willing not to smoke for the duration of the study.
* Not pregnant or breastfeeding.
* Not diagnosed with heart attack, stroke, angina, thrombosis, liver or kidney diseases, diabetes, chronic gastrointestinal disorder or cancer.
* Not currently taking medication to stabilize blood glucose (e.g. acarbose, metformin or sulfonylureas).
* Not started new medication within the last 3 months likely to interfere with energy metabolism, appetite regulation and hormonal balance, including: anti-inflammatory drugs or steroids, antibiotics, androgens, phenytoin, erythromycin or thyroid hormones.
* Do not take medication for blood pressure e.g. diuretics, (beta-blockers, Ca-channel, ACE inhibitors, Angiotensin Receptor blockers)
* Do not have diagnosed hypertension (high blood pressure, systolic blood pressure that is higher than 180 mmHg and or diastolic blood pressure that is higher than 110 mmHg).
* Not diagnosed with arterial fibrillation or any other condition that affects heart rate (e.g. arrhythmia).
* No food intolerance, allergies, hypersensitivity or follow any dietary restrictions (e.g. gluten intolerance, coeliac, lactose intolerance, vegan or vegetarian) that will prevent the ability to follow the test diets.
* Do not have a history substance abuse, or current high alcohol intake (\>28 units/week for males and \>21 units/week for females).
* Able to understand the information sheet and willing to comply with study protocol and able to follow dietary instructions before and during the study.
* Ability to prepare basic meals from ingredients provided.
* No travel arrangements outside UK within the period of data collection.
* Not already participating in a clinical trial.
* Able to give informed written consent.