[Satchin] There also is mounting evidence all over the world that shift work is tightly
linked or increases the risk of certain kinds of cancers, including breast cancer.
So that's why World Health Organization has categorized shift work as a potential carcinogen.
So that's a very serious classification because if we know that we have to stay away from
carcinogens, even in buildings, if there is a carcinogen, there's a potential carcinogen
used as a paint or there is a reason, then we have to put a sticker.
And to think about shift workers, they are actually doing something that's a potential
carcinogen.
They do it almost on a daily basis for many, many years.
So that's why I think now there is increasing awareness how to manage shift work so that
they will stay healthy and will reduce the risk of disease.
[Rhonda] And they're doing something beneficial.
I mean firefighters, nurses, you know, police.
I mean they're helping society, so it's not like you can just eliminate shift work, right?
I mean you need shift work.
[Satchin] No, actually our modern society is actually based on those heroes.
So we actually call them the guardians of our society because they are the ones in the
middle of the night, they are making the economy running, they are the ones who are hauling
trucks, long distance trucks, and they are the ones who are actually transporting cargoes
of a plane or ships.
They are the ones in the middle of the night that are taking care of our health and to
any emergency.
So we have to kind of make sure that these heroes are healthy.
So we have to kind of start thinking how to come up with a healthy heroes program where
we can clearly say these are the lifestyles that they can adopt in relation to their being
productive at work so that they stay healthy.
And one complexity with shift work is shift work is just not one type of shift, it's a
mixture of many different types of shifts.
And, for example, firefighters may be on shift for 24 hours straight, whereas a nurse is
on shift for only 12 hours.
Some of the fast responders may be on shift only for eight hours.
And then for them, for some of them, the shift might change two or three times within a month,
so they may be on a day shift versus night shift, even within the same week.
Whereas in some departments and in some professions they can be on the same shift for three to
four months, which helps them to adapt to that shift.
So in that way I think it will be interesting to bring up this heterogeneity in shift work
and figure out which kind of shift work is more manageable than others and perhaps figure
out how we can help, firefighter kind of shift work versus nurse kind of shift work and first
responders.
[Rhonda] Yeah.
Do we know from any animal evidence...
For example if you take an animal that is, you know, for example, nocturnal, like a rodent,
a mouse, which usually eats at night, you force it to now not eat at night but to be
awake during the day and eat at day and not eat at night.
So if you can shift them to not eat all day, all night, but eat just within a time-restricted
eating window, do we know if they eventually adjust, how long it takes for them to adjust?
Does their metabolism adjust?
Does their circadian rhythm adjust?
[Satchin] Yeah, so those studies have been done and there are many different ways to
look at it.
One is if we just give the same unhealthy high fat, high sucrose diet, instead of giving
them at nighttime for 10 hours, for example, give them during daytime when they're not
supposed to eat, when they're supposed to sleep.
So the bottom line is if mice eat randomly, then any kind of time-restricted eating is
better than that random eating.
So even if they eat during daytime for 10 hours, that still gives them some benefits.
So it's still beneficial.
So there are some concerns with animal experiments.
One is if we feed animals during daytime, definitely they lose some sleep and they just
eat.
Unlike shift workers, they're actually not working throughout the daytime, unless we
force them to really work.
So then it becomes a two-factor intervention.
And then at nighttime when they actually go back to their normal activity, they run around
in the cage.
So in that way they get a sleep deprivation pattern factor into it.
So they are not as healthy as night-fed mice, but at the same time they have a strong sleep
deprivation factor.
So that's why I think among shift workers, coming back to shift workers, if we can control
for how much they sleep during their off time and they can sleep enough, if they come up
with some sleep hygiene and adopt some sleep rituals that help them, and then they adopt
the eating pattern that best suits their shift, then it might help.
[Rhonda] But eating still within a small, more narrow window.
[Satchin] Yeah, still eating within a narrow window.