1. The document discusses various physiological factors that influence hunger and motivation, including stomach contractions, insulin and blood sugar levels, and the role of the hypothalamus in regulating eating behaviors. 2. Social and cultural factors can also influence hunger and eating habits, causing people to eat for reasons other than physiological hunger. 3. Several physiological and evolutionary theories are presented to explain the functions and stages of sleep, as well as sleep disorders like insomnia, sleep apnea, and narcolepsy. Thirst is similarly influenced by physiological mechanisms aimed at maintaining fluid balance in the body.

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Physiological Needs and Motivation
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Dr. Sushma Rathee
assistant clinical psychologist
PGIMER, Chandigarh
email: sushmaratheecp@gmail.com

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Satisfying hunger is one of our most primary needs.
PHYSIOLOGICAL COMPONENTS OF HUNGER:
1st factor:
• Cannon: “stomach contractions, or “hunger pangs,” caused
hunger and that the presence of food in the stomach would
stop the contractions and appease the hunger drive.
• Stomach does have sensory receptors that respond to the
pressure of the stretching stomach muscles as food is piled in
and that send signals to the brain indicating that the stomach is
full and person stop eating, but people who have had their
stomachs removed still get hungry.
Hunger and Motivation

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2nd Factor:
“Insulin response”.
Insulin and glucagon are hormones that are secreted by the
pancreas gland to control the levels of fats, proteins, and
carbohydrates in the whole body, including glucose.
Insulin reduces the level of glucose in the bloodstream, for
example, whereas glucagon increases the level.
Insulin, normally released in greater amounts after eating has
begun, causes a feeling of more hunger because of the drop in
blood sugar levels.

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THE ROLE OF THE HYPOTHALAMUS:
The ventromedial hypothalamus (VMH) involved in stopping the eating
response when glucose levels go up.
Lateral hypothalamus (LH), seems to influence the onset of eating
when insulin levels go up.

5. WEIGHT SET POINT AND BASAL METABOLIC RATE:
Leibel et al., 1995; Nisbett, 1972: believe that the
hypothalamus affects the particular level of weight that the
body tries to maintain, called the weight set point.
The rate at which the body burns energy when a person is
resting is called the basal metabolic rate (BMR) and is
directly tied to the set point.
If a person’s BMR decreases, that person’s weight set point
increases if the same number of calories is consumed.

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SOCIAL COMPONENTS OF HUNGER:
People often eat when they are not really hungry. There are
all sorts of social cues that tell people to eat, such as the
convention of eating breakfast, lunch, and dinner at certain
times.
Cultural factors and gender also play a part in determining
hunger and eating habits.

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MALADAPTIVE EATING PROBLEMS:
OBESITY There are several factors that create obesity, a
condition in which the body weight of a person is 20 percent
or more over the ideal body weight for that person’s height.
Actual definitions of obesity vary.
In recent years, a hormone called leptin has been identified as
one of the factors that controls appetite, which may also play
an important role in obesity.

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THE BIOLOGY OF SLEEP:
One reason for this fact is that sleep is one of the human body’s
biological rhythms, natural cycles of activity that the body
must go through.
THE ROLE OF THE HYPOTHALAMUS:
The release of melatonin is influenced by a structure deep
within the hypothalamus in an area called the suprachiasmatic
nucleus, the internal clock that tells people when to wake up
and when to fall asleep.

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Adaptive Theory of Sleep:
Sleep is a product of evolution (Webb, 1992) according to
the adaptive theory of sleep. It proposes that animals and
humans evolved different sleep patterns to avoid being present
during their predators’ normal hunting times, which typically
would be at night.
Restorative theory of sleep:
“proposing that sleep is necessary to the physical health of
the body and serves to replenish chemicals and repair cellular
damage”.

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REM (rapid eye movement)
sleep
non- REM (NREM) sleep
Types of Sleep

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THE STAGES OF SLEEP

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SLEEP DISORDERS:
1. NIGHTMARES: Bad dreams occurring during REM
sleep.
2. REM BEHAVIOR DISORDER: rare disorder in which
the mechanism that blocks the movement of the
voluntary muscles fails, allowing the person to thrash
around and even get up and act out nightmares.
3. Sleepwalking, or somnambulism: occurs in about 20
percent of the population and is at least partially due to
heredity.
4. NIGHT TERRORS: A rare disorder, night terrors are
more likely in children and also likely to disappear as
the child grows older.
5. INSOMNIA: The inability to get to sleep, stay asleep,
or get a good quality of sleep.

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Cont…
5. Sleep apnea disorder: in which the person stops
breathing for nearly half a minute or more.
6. Narcolepsy sleep disorder: in which a person falls
immediately into REM sleep during the day without
warning.

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Thirst Need:
Thirst is the craving for potable fluids, resulting in the
basic instinct of animals to drink. It is an essential
mechanism involved in fluid balance.
Decreased volume:
two types of thirst and is defined as thirst caused by loss of
blood volume (hypovolemia) without depleting the
intracellular fluid. This can be caused by blood loss,
vomiting, and diarrhea. This loss of volume is problematic
because if the total blood volume falls too low the heart
cannot circulate blood effectively and the eventual result is
hypovolemic shock.

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The vascular system responds by constricting blood vessels
thereby creating a smaller volume for the blood to fill. This
mechanical solution however has definite limits and
usually must be supplemented with increased volume. The
loss of blood volume is detected by cells in the kidneys and
triggers thirst for both water and salt via the renin-
angiotensin system.

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