Sleeping seven to eight hours
a night linked to taking fewer
sick days
Adults who say they sleep between seven and
eight hours per night miss fewer work days due
to sickness than others, according to a Finnish
study.
The researchers calculate that if insomnia,
apnea and other kinds of sleep disturbances
were eliminated, the total cost of worker sick
days could be cut by 28 percent.
“Previous studies have already shown
associations between insomnia and sickness
absence and there is some evidence regarding
the association between sleep duration and
sickness absence,” said lead author Tea
Lallukka, a special researcher at the Finnish
Institute of Occupational Health in Helsinki.
But the new study looks at a nationally
representative sample of people, which also
covers many different types of employment,
Lallukka told Reuters Health by email.
She and her coauthors used data from a
national survey of Finnish workers over age 30
in 2000, including 1,875 women and 1,885
men.
The participants answered questions about
their sleep disturbances, insomnia symptoms,
daytime sleepiness and the average hours of
sleep they got per 24 hours and had medical
exams to detect mental or physical illnesses.
The researchers also looked up their work
absences from 2000 through 2008 in the Social
Insurance Institution of Finland database,
which registers sickness absences.
Taking age into account, men who reported
frequent insomnia symptoms had more than 10
sick days per year, compared to five absences
for men who never or rarely had symptoms.
Results were similar for women and for most
types of sleep disturbance.
Sleeping between seven and eight hours per
night, which included most of the adults in the
study, was associated with the fewest sick
days per year. Ten percent of women and 13
percent of men reported sleeping an average of
six hours per night, and less than three percent
reported five hours or fewer.
“It is well known that chronic sleep deficiency
causes several daytime impairments,” said
Borge Sivertsen, a researcher at the Norwegian
Institute of Public Health, headquartered in
Oslo, Norway.
“Our ability to sustain attention and maintain
peak cognitive performance is significantly
reduced if we are sleep deprived over longer
periods,” Sivertsen told Reuters Health by
email. He was not involved in the new study.
For the Finnish men, optimal sleep duration
was 7 hours 46 minutes per day, with women
peaking at 7 hours 38 minutes per day,
according to the results published in the journal
Sleep.
“Those sleeping 5 hours or less or 10 hours or
more were absent from work 5 to 9 days more
each year, as compared to those with optimal
sleep,” Lallukka said.
The relationship held even when age, education
level, various physical and psychosocial
working conditions, health behaviors and
clinically assessed physical and mental health
conditions were accounted for, she said.
People who sleep the optimal amount may do
other things to reduce their risk of sickness
absences too, said Paula Salo of the University
of Turku in Finland and the Research Team for
Psychosocial Factors at the Finnish Institute of
Occupational Health.
“People who get the sleep they need may in
general take better care of their own health and
wellbeing, which obviously maintains work
ability, too,” Salo told Reuters Health by email.
“Perhaps they, for example, maintain more
regular schedules for sleeping, eating,
exercising, etc., that support wellbeing. They
may also have, for example, more efficient
strategies for coping with stress, which very
easily disrupts sleep, enabling them to sleep
well and preventing them from falling ill,” said
Salo, who was not part of the new study.
Sleep disturbances can result in huge costs due
to sickness absence, decline in cognitive
functioning and productivity, accidents at work
while commuting, Lallukka said
“The results of this new study are broadly
consistent with those of comparable studies in
the U.S. in showing that disturbed sleep is a
very common and much more serious problem
in the general population than is generally
appreciated,” said Ronald C. Kessler of Harvard
Medical School in Boston, who wasn’t involved
in the study. Lallukka noted that individual
sleep needs may vary, and one person should
not necessarily apply the results of the
population-level observational study to their
day-to-day routine.
“If you feel you do not perform optimally, or
don’t feel rested when you awake, this might be
an indication that you do not get enough
sleep,” Sivertsen said.
There are many good treatment options,
including cognitive behavioral therapy, which
does not involve drugs, he added.
“If one is not tired, and functioning fine, and
find the sleep sufficient and refreshing, there is
no need to worry,” Lallukka said.
- Reuters