The effect of either the consumption of 1 or 3 small meals, with a high or low glycaemic load, compared to no meal during the night shift on alertness levels, gastrointestinal complaints and glucose levels.

Night shift workers have a 30 percent higher risk of making (medical) errors or
having accidents than day shift workers. This is mainly the result of shift
work-related fatigue which is related to lower alertness levels. Alertness
levels are at lowest between 2:00h and 6:00h in the early morning, and eating a
large meal impairs alertness levels even further. Not eating, or eating one or
more small meals during the night shift could improve alertness levels.

The primary objective of this study is to investigate the effect of either the
consumption of 1 or 3 small meals compared to no meal during the night shift on
alertness levels.
Secondary objectives of this study are to investigate the effect of either the
consumption of 1 or 3 small meals compared to no meal during the night shift on
gastrointestinal complaints and glucose levels and to investigate the effect of
low glycaemic loaded meal(s) compared to high glycaemic loaded meal(s) during
the night shift on alertness levels, gastrointestinal complaints and glucose
levels.

2-armed randomized cross-over intervention study, where each study arm consist
of three intervention periods.

During two of the three intervention periods, nurses will receive either 1
small meal or 3 small meals during the night shift. During one of these two
intervention periods the meals consist of carbohydrates high in glycaemic load
and during the other intervention period the meals consist of carbohydrates low
in glycaemic load. During a third intervention period participants both study
arms will receive no meal during the night shift as a control.

Participation in the study will not bring any risks. Also patient safety will
not be jeopardized. The burden for participants will be kept as low as
possible. The placement of the continuous glucose monitor (CGM), though quite
non-obtrusive, can be considered as a burden for the participants. The placing
of each piece of equipment will be done by experienced researchers and will be
secured by well-practiced measures to minimize issues the participant may
encounter. The calibration of the CGM may be considered a burden due to the
finger prick that is required four times a day by a glucose meter. Participants
will have to invest approximately 5 hours in the study, therefore time
investment could be a potential burden. Also following the dietary regimen can
be considered as a burden. As a personal benefit, participants get more insight
in their eating patterns, alertness levels and glucose metabolism. The results
of this study will provide information about the effects of meal frequency on
the nurses* alertness levels, gastrointestinal complaints and glucose
metabolism. With the results of this study we want to optimize dietary
guidelines for shift workers in order to improve the fitness and wellbeing of
shift workers and to reduce the risk of making (medical) errors or having
accidents.