Biological Rhythms.

Question 1

What is a biological rhythm?

Answer 1

Distinct patterns of changes in body activity that conform to cyclical time periods, governed by endogenous pacemakers and exogenous zeitgebers.

Question 2

What is a infradian rhythm?

Answer 2

more than 24 hours.

Question 3

What is a circadian rhythm?

Answer 3

24 hours.

Question 4

What is the ultradian rhythm?

Answer 4

less than 24 hours

Question 5

What is an endogenous pacemaker?

Answer 5

Internal body clocks that regulate many of our biological rhythms.

Question 6

What is the SCN?

Answer 6

Located in the hypothalamus, is the regulator of the sleep wake cycle. It receives information from the optic nerve via the optic chasm, which sits below it.

Question 7

How does the SCN regulate sleeping and waking?

Answer 7

-It receives information regarding the level of light and passes this to the pineal gland.
-In the night, the pineal gland releases melatonin.
-In the day, it inhibits the secretion of melatonin.

Question 8

What are Morgan’s Hamsters?

Answer 8

-Hamsters had their SCNs removed.
-This caused their nocturnal patterns to cease.
-When new fetal cells were implanted, they regained their circadian rhythms.
-However this is on animals so the question of generalisation ability.

Question 9

Evaluating EP research?

Answer 9

-SCN research may obscure the other body clocks, such as peripheral oscillators, which work with the SCN but also independently.
-It is almost impossible and extremely rare to study EPs completely without EZs. In Michael Siffre’s cave study, the artificial lights could have acted as EZs.
-Unethical animal research.

Question 10

What are exogenous zeitgebers?

Answer 10

External cues that may affect or entrain our biological rhythms, such as the influence of light on the sleep/wake cycle.

Question 11

What is a free running rhythm?

Answer 11

the activity cycle generated by an endogenous clock that is not reset

Question 12

Campbell and Murphy?

Answer 12

-Shone light onto the back of participant’s knees, and managed to alter their circadian rhythms.
-This shows that light can reach the brain without going through the eyes.

Question 13

What do jet lag studies tell us about EZs?

Answer 13

-Show that if you eat and sleep in the new locations, you will more effectively entrain the circadian rhythm.
-Importance of social cues.

Question 14

Miles et al?

Answer 14

-Case study of a blind man.
-Circadian rhythm was 25 hours, despite being exposed to social cues.
-Suggests that light is the main EZ.

Question 15

Evaluating EZs?

Answer 15

-People living in the arctic circle have similar circadian rhythms all year round, despite being in darkness for almost 6 months.
-Suggests mainly endogenous pacemakers that control rhythms.

Question 16

What is the sleep wake cycle?

Answer 16

A daily cycle of biological activity based on a 24-hour period (circadian rhythm) that is influenced by regular variations in the environment, such as the alternation of night and day.

Question 17

Siffre’s cave study aim?

Answer 17

to investigate the effect on the sleep wake cycle with no EZs.

Question 18

Siffre’s cave study procedure?

Answer 18

-Stayed in Texas midnight cave for 6 months.
-When he woke up, he would ring the research team and the lights would turn on.
-When he felt tired, he would ring again and the lights would switch off.
-He also did daily tests on his memory and eyesight.

Question 19

Siffre’s cave study findings?

Answer 19

-Short term memory, eyesight and mental health all got worse.
-For the first 35 days, his cycle was 26 hours.
-Then his next cycles were longer, before returning to 26 hours on day 63.
-After nine weeks, it became largely varied.
-The it returned to 26 hours on day 150.

Question 20

Siffre’s cave study strengths?

Answer 20

-Done over six months so irregularities could be seen.
-Lots of quantitative and qualitative.

Question 21

Siffre’s cave study weaknesses?

Answer 21

-Artificial lights could have acted as EZs.
-Only 1 participant so lacks generalisability.

Question 22

Evaluation of circadian rhythms?

Answer 22

• individual differences, cycles can vary from 13 to 65 hours and reach peaks at different times. The idea of a general rule for a sleep-wake cycle seems unlikely.

-Chronotherapeutics, the study of how timing affects drugs is a useful application, for maximum absorption and distribution.

-Helps to improve shift work. Discovered the circadian trough at 6am. Has economic value because can maximise productivity and minimise accidents. Continuous disruption to cycle causes stress and high blood pressure.

Question 23

What is the menstrual cycle?

Answer 23

Time period when blood, tissue and unfertilized egg leaves the body

Question 24

Menstrual cycle hormones?

Answer 24

FSH= causes egg to mature.
LH= egg is released (ovulation).
Oestrogen= thickens the womb lining.
Progesterone= maintains lining.

Question 25

What is the EP in the menstrual cycle?

Answer 25

oestrogen and progesterone.

Question 26

Stem and McClintock research into synchronisation of menstrual cycles?

Answer 26

-Studied 29 women with irregular periods.
-They gathered samples of pheromones from sweat from 9 of the women. They were treated with alcohol and rubbed onto the upper lip of the other 20 women.
-68% of the women experienced a cycle change towards the odour donor.

Question 27

What is SAD?

Answer 27

seasonal affective disorder, occurs in winter or northern climates.
-Triggered by prolonged secretion of melatonin from the pineal gland, caused by the lack of daylight.
-Melatonin secretion has be linked to decreased serotonin.

Question 28

Evaluating infradian rhythms?

Answer 28

-Evolutionary basis= synchronising menstrual cycles means getting pregnant at the same time, so childcare can be shared. The children have a better survival chance.
-Many factors affect menstrual cycle.
-Light therapy has been effective in treating SAD, but only temporarily.

Question 29

How long is the stages of sleep?

Answer 29

90 minutes

Question 30

Stage 1 of sleep?

Answer 30

-Light sleep
-The brain emits alpha waves–> consistent with a relaxed state of wakefulness

Question 31

Stage 2 of sleep?

Answer 31

A sleep deeper than that of stage 1, characterized by a slower, more regular alpha wave pattern, along with momentary interruptions of “sleep spindles.”

Question 32

Stage 3 of sleep?

Answer 32

Deep sleep begins, delta waves are emitted.

Question 33

Stage 4 of sleep?

Answer 33

the deepest stage of sleep, during which we are least responsive to outside stimulation. Delta waves

Question 34

Stage 5 of sleep?

Answer 34

REM sleep, the body is paralysed but the brain is similar to when awake. Theta waves.

Question 35

Why are EEGs used to investigate sleep?

Answer 35

-High temporal validity.
-Do not cause pain so don’t disrupt sleep.

Question 36

Derment and Kleitman?

Answer 36

Aim: to determine the connection between dreaming and eye movements
7 adult males and 2 adult slept in a lab, hooked up at an EEG and woken at diff. times and asked about their dreams. They were woken 5 or 15 minutes into REM and asked if they had been dreaming for 5 or 15 minutes.
All had REM periods for various lengths (3 to 50 mins)
-REM sleep is predominantly associated with dreaming
-Patients could choose fairly accurately dream lengths
-There was correlation between dream content and eye movements

Question 37

Weaknesses of Dement and Kleitman?

Answer 37

-The self report of
-dreaming & content was subjective- Sample size and makeup (cannot generalize)
- No background provided for Ps (can be Ethnocentric)
- Method of waking subject may have influenced ability to recall dreams
- Correlation does not mean causation
- Lacks ecologicl valdiity.
- Small sample.

Question 38

Evaluating ultradian rhythms?

Answer 38

-Significant variations within people (shown by Tucker et al), suggests a generalised sleep does not exist.
-Helps to understand age related problems. Slow wave sleep decreases with age. The growth hormone is produced in slow wave sleep. Explains issues such as lack of alertness as we get older.