the nation’s sleep labs, far more common than total sleep
deprivation is what researchers variously call partial sleep loss,
sleep restriction or short sleep. Whatever they call it, they’re
referring to chronically cutting one’s sleep short by just an
hour or two a night. The first study to look closely at the health
effects of partial sleep was published in The Lancet in 1999.
In that study, Van Cauter’s team found that levels of leptin,
a hormone that regulates hunger and appetite, dropped 19
percent during a period of partial sleep deprivation.
The cardiometabolic trap
Subsequent studies have confirmed the effects of partial sleep
loss on hormone regulation and have led to a burgeoning
of research on the role of sleep in obesity, diabetes and
cardiovascular disease — a tangled triumvirate of sickness and
mortality that are key elements of what researchers sometimes
refer to as cardiometabolic disease. In a 2012 article published
in the American Journal of Human Biology, UC biomedical
anthropologist Kristen Knutson, PhD, reviewed research on
sleep and cardiometabolic health and concluded that sleep
restriction leads to “substantial and clinically significant
changes in appetite regulation, hunger, food intake, glucose
metabolism and blood pressure control.” Knutson also found a
significant association between short sleep duration (less than
six hours per night, in most studies) and either more obesity
or a higher body mass index. Adolescents and children showed
a stronger association, suggesting they may be especially
vulnerable to the effects of lost sleep.
One way in which lack of sleep may
thwart cardiometabolic health is by
skewing people’s dietary choices. In a 2011
study published in the American Journal
of Clinical Nutrition by a large multicenter
team, healthy men and women who were
restricted to just four hours of sleep per
night over six nights took in significantly
more calories, particularly from fat, than
their well-rested counterparts — and they
didn’t make up for it by burning more
Another study, conducted by Arlet
Nedeltcheva, MD, and colleagues at UC
and published in the American Journal
of Clinical Nutrition in 2009, found that
adults who were allowed to sleep only 5. 5
hours per night for two weeks indulged in
more snacks than their counterparts who
enjoyed 8. 5 hours of sleep each night.
Likewise, in a 2012 yet-to-be-published
study that drew on data from the CDC’s
sleep complaints including difficulty falling asleep, difficulty
staying asleep, non-restorative sleep and daytime sleepiness.
Every complaint, they found, was significantly associated with
greater total caloric intake.
Less money, less sleep
Video: Dr. Lauren Hale discusses the links between
socioeconomic status and sleep.