In Colorado, a person aged 21 or older may
now grow up to six plants privately and may
possess more than an ounce of marijuana for
recreational use but may not smoke it in pub-
lic. Commercial sales to recreational users are
expected to begin in 2014 and will be taxed, yetmany questions remain about whether to limit
potency, how to regulate labeling, and how to
prevent use by teenagers. Opponents and fans
of legalization have hired lobbyists to argue their
case, and the new laws are likely to be chal-
lenged in the courts.C
onflicting laws on marijuana show how
deeply divided Americans are about this
widely used drug. This division is by no
means confined to the United States. In
March 2013, the president of a United
Nations board that monitors narcotic pro-
duction and use stated that implementation
of the Colorado and Washington decisions
would violate international laws and trea-
ties. Yet many countries, including Canada,
Spain, Italy, Portugal, Israel, Austria,
Finland, the Netherlands, and Belgium,
have either decriminalized possession of
small amounts of marijuana or made it
legally available to those who have demon-
strated a medical need.
Marijuana is just one of many drugs
used throughout the world to alter con-
sciousness, the awareness of oneself and
of the environment. But consciousness also
changes in predictable ways without any
help from drugs. Each day we all experience
swings in mood, alertness, and efficiency.
Each night, we all undergo a dramatic
shift in consciousness when the ordinary
rules of logic are suspended in the dream
world of sleep. Performance and mood may
be subject to much longer cycles as well,
stretching over a month or even a season.
In this chapter, we will see that fluc-
tuations in subjective experience are
accompanied by ups and downs in brain
activity, hormone levels, and neurotransmit-
ter levels, and that the mental and physical
aspects of consciousness are as intertwined
as sunshine and shadow. We will begin with
a discussion of the body’s natural rhythms,
which ebb and flow over time. Next we
will zoom in on one fascinating state of
consciousness: dreaming. And then we will
explore what psychologists have learned
about two techniques used to alter con-
sciousness deliberately: hypnosis and the use
of recreational drugs. Our goal is to give you
a better understanding of the human fascina-
tion with altered states of consciousness and
why some people use drugs to achieve them.
Are all drugs equally dangerous? Should
there be different policies for medical, rec-
reational, and religious use? Are current
prohibitions realistic? Does legalization
carry dangers? We will return to these issues
at the end of the chapter.
You are about to learn...
• how biological rhythms affect our physiology
and performance.
• why you feel out of sync when you fly across
time zones or change shifts at work.
• why some people get the winter blues.
• how culture and learning affect reports of “PMS”
and estimates of its incidence.Biological Rhythms:
The Tides of Experience
The human body goes through dozens of ups
and downs in physiological functioning over the
course of a day, a week, and a year, changes that
are known as biological rhythms. A biological clockCircadian Rhythms
Periodic, more or less
regular fluctuations in
a biological system;
they may or may not
have psychological
implications.