Night-shift workers who eat only in the day may cut diabetes risk - New Scientist

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People who work overnight are more likely to develop type 2 diabetes, but the risk may be reduced by eating only between 7am and 7pm

Health 3 December 2021

By Clare Wilson

ANKARA, TURKEY - MARCH 31 : A worker uses a metal cutter on a rail on Ankaray subway line during night shift in Ankara, Turkey on March 31, 2018. Long rapid transit line of the Ankara Metro system has been operating for 23 years. Ankaray operates approximately 180 runs on daily basis, with 11 cars. Length of the transit line reaches about 9 kilometers. Night shift workers compete against time while cutting old rails and replacing them with the new ones until the first run in the morning. (Photo by Mustafa Kamaci/Anadolu Agency/Getty Images) — A night-shift worker using a metal cutter on a subway line in Ankara, Turkey

Mustafa Kamaci/Anadolu Agency/Getty Images

People who work night shifts may be able to avoid the resulting harm to their blood sugar control by eating only in the daytime.

A small trial in people who simulated a night-working pattern by staying awake all night found that those who ate only between 7am and 7pm had normal blood sugar regulation after a single test meal. In this regimen, people woke up during the day to eat, but abstained from food during night-shift hours. But those who ate some meals at night, as is common in people who work night shifts, had worse blood sugar control.

The body tries to keep blood sugar within a certain range, as high blood sugar damages blood vessels, but if levels gets too low, cells go short of energy. Poor blood sugar control can progress to type 2 diabetes, which usually needs managing with diet and medications and can lead to heart disease.

Previous work has found that night-shift workers are more prone to poor blood sugar control and type 2 diabetes. So Frank Scheer at Brigham and Women’s Hospital in Boston, Massachusetts, and his colleagues wondered if they could counteract the effects on blood sugar by keeping eating patterns more aligned with people’s normal “body clock”.

They asked 19 volunteers to eat a carefully measured test meal for breakfast, after which their blood sugar levels were measured. Then, the participants gradually shifted their waking patterns so that after three days, they were in a fully reversed pattern, sleeping in the daytime. The next day, the group was split in two.

About half had some meals in the daytime and some at night, which is how many night-shift workers behave. They then had the same test meal for their 7pm “breakfast”; their blood sugar levels rose by 19 per cent more than they did after the same test was carried out at the start of the experiment.

The others were given food only between 7am and 7pm, and were woken up twice during their main sleep in the day to eat a meal. They had no significant change in blood sugar response to the test meal.

Most night-shift workers wouldn’t like to wake up in the day to eat meals, says Scheer, so his group is going to test a new regime, in which people fit in all their food immediately before and after sleeping, while still keeping meals to between 7am and 7pm. “The next step is to develop a more practical meal schedule,” he says.

While it could be unpleasant to work all night without a meal, says Scheer, it may help to eat just small amounts and avoid carbohydrate-rich food that raises blood sugar quickly.

Jonathan Cedernaes at Uppsala University in Sweden says that while the results are interesting, “we don’t know based on this data how these metabolic outcomes would change if someone was in a fixed night-time schedule for a week”.

Journal reference: Science Advances, DOI: 10.1126/sciadv.abg9910

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