oh that hot cup of morning Joe caffeine
is often cited as the most widely used drug in the world it's a naturally
occurring substance found in plants and foods and both organic and processed
foods caffeine though is a stimulant that works by blocking adenosine inside
your cells and here's how this works adenosine is produced in the cells of
the brain in other organs and it's it's a chemical that's involved in inducing
or bringing on sleep by slowing the activity of the cell caffeine is similar
in structure to the adenosine molecule so when you drink coffee and digest it
the caffeine in the coffee travels to your brain and binds to the cells and
blocks the adenosine from binding without the adenosine to slow things
down your adrenal glands get the signal to release the fight or the flight or
fight hormone epinephrine epinephrine also known as adrenaline then acts to
increase alertness increase your heart rate and constrict blood vessels so this
is the high that you get from caffeine it's that boost of adrenaline also as an
aside the constriction of blood vessels that follow the caffeine consumption is
the basis for caffeine being a part of headache medicines it constricts the
blood vessels in the brain through the epinephrine release which gives the
tissues more space and relieves some of the tension that was producing the
headache so back to the caffeine and sleep caffeine affects your sleep in a
couple of different ways first it extends your sleep latency which we know
is the time that it takes for you to fall asleep it also shortens the total
amount of time that you sleep and the older that you
get the more sensitive you are to these effects similar to alcohol caffeine is a
diuretic which causes the body to lose water so how much caffeine does it take
to affect your sleep depending on the amount of time between consuming the
caffeine and going to sleep I'd say anything greater than 200 milligrams of
caffeine would create a delayed sleep effect a moderate dose of caffeine would
be anything between say two hundred and three or four hundred milligrams a day
heavy caffeine consumption would be considered around 500 milligrams a day
so what does that mean exactly well let's look at typical caffeine
concentrations in foods as you can see there's a lot on this page but I just
wanted to point out a few things to give you a ballpark of what kind of things we
consume and how it compares to a moderate caffeine consumption or low or
high so if you're one you like Starbucks Coffee you can see that the smallest on
the short is a hundred and eighty milligrams which that's just a little
under what under the 200 which is a dose that can delay your sleep but if you
prefer the grande version of it the 330 milligrams
now you're into a moderate dose of caffeine
also everything else on this list is lower in concentration than coffee
including Mountain Dew which I'd always heard was what you needed to drink if
you really needed to stay awake but you really need to drink a few of them as
Mountain Dew with 12 ounce can only contains about 55 milligrams of caffeine
which is less than a cup of coffee and another thing on this list that I
thought was significant is the Hershey's chocolate bar I have here that it's one
and a half ounces for sorry four for one and a half ounces of the bar you get
nine milligrams of caffeine well okay if that if you can discipline yourself to
only eat one of those little squares but for an eight ounce bar the kind that you
buy in the store now you're getting 46 milligrams of
caffeine you know that's not a huge dose of caffeine but it may make a difference
if you were to have that in the evening say as opposed to in the morning
keep in mind imported coffees and teas usually carry a higher caffeine
concentration and the brewing method that you use can affect the caffeine
content once you consume the caffeine its digests it through the stomach and
small intestines and enters the bloodstream within 30 minutes to an hour
and this is a relatively rapid response and in fact this is one of the reasons
why a cup of coffee is so popular as that morning kick to get you going let's
look at some of the negative effects of caffeine we have reduced appetite
insomnia rapid or racing heartbeat anxiety headache nervousness
irritability and you can have gastrointestinal problems like nausea or
diarrhea the half-life is the amount of time it takes for something to decrease
to half its original quantity the half-life of caffeine varies among
different studies but this generally believed to be
somewhere between three and a half to six hours it can take longer in some
people with certain medical disorders or who are under the influence of certain
medications for example birth control pills can inhibit or slow the half-life
of caffeine making it so that it takes five to ten hours for the amount of
caffeine in your bloodstream to decrease by half pregnancy and liver disease can
also significantly extend the half-life of caffeine so let's look at a practical
example suppose you were to drink at all Starbucks coffee at 9:00 a.m.
That size
has 230 milligrams of caffeine if we assume the caffeine carried a half-life
of 5 hours you'd have approximately 130 milligrams of caffeine in your system at
2:00 p.m. that afternoon just from that single cup of coffee and at 9:00 o'clock
in the morning now this is an approximation but because of the
variability in how we metabolize caffeine some experts recommend that
that you not consume any caffeine after noon and I happen to be in that camp I
usually recommend to people that you have your last drink of coffee before 12
o'clock in the afternoon but I realize there are those people who are able to
drink tons of coffee even in the evening and never seem to have trouble falling
asleep and we really still don't know
everything about caffeine even experts are unsure as to whether the varied
responses are because of tolerance cut to the caffeine or it could simply be
that some people metabolize caffeine at a faster rate and and are therefore less
sensitive to the sleep interfering properties my own thought is that people
who drink caffeine or drink coffee after 6:00 p.m.
probably are not planning to
go to bed 3 hours later and it may just be that those people who
do drink numerous cups of coffee throughout the day and continue into
early evening of this tolerant to the stimulating effects of the caffeine and
because they normally fall asleep later in the evening they're just not aware
that it's the caffeine is actually.
