Altered postprandial hormone and metabolic responses in a simulated shift work environment

Area of Science:

• Chronobiology
• Metabolic Health
• Shift Work Research

Background:

• Circadian rhythm disruption in night shift workers is linked to health issues.
• Inappropriate hormonal and metabolic responses to meals during night shifts may mediate these problems.

Purpose of the Study:

• To investigate the impact of a simulated night shift on hormonal and metabolic responses to meals.
• To assess the time course of adaptation to eating during a phase-shifted schedule.
• To evaluate the influence of pre-meal composition on postprandial responses.

Main Methods:

• Twelve healthy subjects underwent a simulated 9-hour phase advance.
• Test meals were consumed at the same clock time (1330 h) but different body clock times.
• Measured parameters included plasma glucose, non-esterified fatty acids (NEFAs), triacylglycerol (TAG), insulin, C-peptide, proinsulin, glucose-dependent insulinotropic polypeptide, and urinary 6-sulphatoxymelatonin.

Main Results:

• Postprandial glucose and insulin responses were unaffected by the phase shift with a low-fat pre-meal.
• Basal plasma NEFAs were lower immediately after the phase shift (P < 0.05).
• Incremental triacylglycerol (TAG) responses were significantly higher (P < 0.05) immediately after the phase shift, with partial reversion after 2 days.

Conclusions:

• Adaptation to eating meals during a simulated night shift requires at least 2 days.
• Nutritional content of pre-meals significantly influences postprandial responses during phase shifts.
• Findings may partially explain increased cardiovascular disease risk in shift workers.