'Morning people' who consumed caffeine during the day have
been found to be the most likely to be disrupted during their
Despite the positive effects it has for us all throughout the day,
a new study has revealed that day time caffeine consumption could
be adversely affecting how well we sleep at night.
The researchers at Stanford University in the US surveyed 50
college students to find what type of sleeper caffeine affects the
most. The students were asked to record their caffeine consumption
and their sleeping and waking times for a week. Each of them wore
wrist devices that monitored their movements, to assess whether
they had periods of wakefulness after they had fallen asleep. The
researchers also measured caffeine levels in the students' saliva
over the week.
This is the first time caffeine intake has been linked with
'chronotype', which is the categorizing of people by the time of
day they are most alert and active. The findings are preliminary
and more research is needed to confirm them, the researchers
Study researcher Jamie Zeitzer, an assistant professor of
psychiatry and behavioral sciences at Stanford University, said:
"it didn't matter how much caffeine they had, they slept well
whenever they finally hit the sack."
"However, for the early risers, the more caffeine in their bodies,
the more time they spent awake during the night after initially
falling asleep. This was not seen in the night owls."
Bodies respond in differing ways to caffeine intake, and some
people's bodies can clear caffeine within a few hours. However,
lunchtime coffee may still be in the system of other people even
late at night.
Caffeine consumption has also been linked to how well children can
sleep, with a study that came out in December 2010 finding that the
more caffeine children consumed, the less they slept. According to
the research 75 per cent of children consume caffeine on a daily
basis, which can lead to day time grogginess if sleep is
Posted by Michael Ewing