An evening milkshake spiked with the amino acid
tryptophan may help clear the morning mental fog
of the sleep-deprived, preliminary research suggests.
In a study of 28 healthy young adults, researchers
found that accompanying an evening meal with a milkshake
containing a protein powder called alpha-lactalbumin
-- which delivers a high concentration of tryptophan
-- seemed to improve morning alertness among participants
who had mild sleep problems. "Good" sleepers, on
the other hand, showed no such benefit.
The findings, published in the American
Journal of Clinical Nutrition, suggest that
the supplement sharpened certain participants' mental
acuity by improving their sleep.
However, much more research is needed before tryptophan-laced
milkshakes can be recommended as a sleep aid, according
to lead study author Dr. C. Rob Markus of the University
of Maastricht in the Netherlands.
Alpha-lactalbumin, or A-LAC, is a protein derived
from the whey component of milk. It contains a high
concentration of the essential amino acid tryptophan,
a protein building-block best known for its sleep-inducing
effects. In the body, tryptophan serves as a precursor
for the brain chemical serotonin, which, among other
things, is thought to help regulate sleep.
Tryptophan is found in foods such as beef, chicken,
dairy products and, most famously, turkey -- which
is often blamed for the near-coma that follows Thanksgiving
dinner. In reality, however, the relatively low
concentration of tryptophan in turkey and other
foods is unlikely to affect the brain because it
must compete with other amino acids and nutrients
In their study, Markus and his colleagues examined
whether an A-LAC protein powder, with its high concentration
of tryptophan, could increase the ratio of tryptophan
to other amino acids in participants' blood -- and
whether there would be any difference in their mental
alertness the next morning.
The protein powder, marketed as BioPure, was supplied
by Eden Prairie, Minnesota-based Davisco Foods International.
Fourteen men and women with mild sleep problems,
and 14 others without sleep complaints took part
in two experiments on separate evenings -- one in
which they consumed a tryptophan-fortified milkshake
with dinner and later for a snack, and one in which
they had "placebo" milkshakes that did not contain
the A-LAC supplement.
The next morning, participants took a computerized
test that measured their mental reaction times,
while electrodes placed on their scalps recorded
their brain activity.
Markus and his colleagues found that participants'
blood levels of tryptophan were more than twice
as high on the night they dined on the supplemented
milkshakes compared with the placebo milkshakes.
More importantly, men and women who normally had
sleep problems performed better on the mental-alertness
test on the morning after having the tryptophan-containing
milkshakes. On the other hand, tryptophan made no
difference to the performance of the 14 participants
with no sleep problems.
It's likely, according to Markus and his colleagues,
that improved sleep explains the better test performance.
They found that people who were normally "poor sleepers"
reported less morning grogginess the day after having
the tryptophan-fortified milkshakes.
However, it's too soon to start recommending the
A-LAC supplement to the sleep-deprived, Markus told
"A lot of research needs to be conducted before
making any claims," he said.
Among the remaining questions is how the souped-up
shakes might affect people with more-significant
sleep problems. And in general, Markus noted, the
precise role of tryptophan and serotonin in sleep
is not fully understood. Though they appear to help
regulate sleep-wake rhythms, he said, the magnitude
of the influence is not clear.
SOURCE: American Journal of Clinical Nutrition,