Biological Rhythms

Question 1

Biological rhythms

Answer 1

Repetitive biological processes that happen internally

Question 2

3 different types of bio rhythms

Answer 2

Ultradian
Circadian
Infradian

Question 3

Ultradian cycles

Answer 3

Occur multiple times in 1 day and are ultra quick
Example: blood circulation

Question 4

Circadian cycles

Answer 4

Occur once a day
Also known as sleep cycle

Question 5

Infradian cycle

Answer 5

Occur in cycles longer than a day: can range from across multiple weeks/ months
Example: Menstruation

Question 6

What drives bio rhythms?

Answer 6

Factors that are
Exogenous (occur in the environment such as light)
Endogenous (occur internally such as with the release of hormones)

Question 7

Key research

Answer 7

Czeisler

Question 8

Where and who did Czeisler study?

Answer 8

153 male potash factory workers in Utah

Question 9

In Czeislers study, what was the original schedule for the workers?

Answer 9

85 worked rotational phase advancing shifts
68 worked non rotating day/swing shifts

Question 10

Phase advance

Answer 10

when you have to bring FORWARD in the day the time you go to bed
Aka going to bed early

Question 11

A phase advance rotational shift means…

Answer 11

Workers would have a shift earlier than previously; working in night then working in afternoon then working in morning
So they’d go to bed EARLIER = advance circadian rhythm

Question 12

Phase delay

Answer 12

When you bring BACKWARD in the day the time you go to bed
Aka going to bed later

Question 13

First questionnaire Czeisler handed out to factory workers

Answer 13

Asked about happiness, productivity and opinion on their current shifts

Question 14

How many workers on the rotational shift had previously fallen asleep at work? (From Czeislers 1st questionnaire)

Answer 14

29%

Question 15

Czeisler’s intervention

Answer 15

Gave presentation to managers + workers
Suggests 85 rotational shift workers change to investigate:
All had phase delay shift but divided into 2 groups:
Rotate 7 days
Rotate 21 days

Question 16

Czeisler’s second questionnaire

Answer 16

About workers new happiness, health and preferences with the new schedule they were assigned: all phase delay but some rotated 7 days compared to 21 days

Question 17

What did post intervention find out?

Answer 17

Significantly preferred phase delay
Significantly happier rotating every 7 days than 21 days
21 phase delay = significantly happiest and healthiest compared to any other schedule

Question 18

Czeisler’s 9 month analysis

Answer 18

Analyse productivity and turnover; long term effects of his intervention

Question 19

Czeisler’s 9 month analysis findings

Answer 19

The turnover for non rotating shift workers was the same for 21 phase delay rotating shift workers

Question 20

Conclusion of Czeisler

Answer 20

To minimise the impacts of disrupted circadian rhythms:
Disrupt the rhythm less frequently
Disrupt by phase delay (rhythm occurs later in the day) is preferred because we have 25 hr internal clock

Question 21

Additional research

Answer 21

Siffre - living underground
Preckel - investigate effect of sleep schedules on academic performance
Melatonin
Light boxes

Question 22

How did Siffre complete his investigation?

Answer 22

Lived in a cave for 2 months to control for exposure to exogenous cues
Called research team to report when he had woken up, his eating habits, his blood pressure reading (collected data in these forms)

Question 22

What did Siffre aim to investigate?

Answer 22

To measure the body’s internal sleep cycle (circadian rhythm) by isolating it from all exogenous cues such as seasons, light, temperature, knowledge of time etc

Question 23

Siffre’s conclusion

Answer 23

The body followed a 25 hour sleep-wake cycle
Suggesting humans have an independent 25 hour body clock, which is independent of exogenous terrestrial cycles

Question 24

What did Preckel aim to investigate?

Answer 24

Investigate the effect of German high school students sleep cycles on their academic performance

Question 25

Preckel’s sample

Answer 25

272 German high schoolers

Question 26

What is a chronotype?

Answer 26

A theory that someone can favour going to bed and waking up early (lark chronotype)
Or going to bed and waking up late (owl chronotype)

Question 27

Preckel’s procedure

Answer 27

Gave a chronotype questionnaire to students (find out if they’re an ‘owl’ or ‘lark’
Give standardised cognitive test
Give questionnaire to parents to find out their academic habits; motivation, conscientiousness etc

Question 28

Why did Preckel give a survey to the high schooler’s parents and the cognitive test to the students?

Answer 28

So he could collect data on the individual differences across the sample, such as cognitive ability, motivation and conscientiousness that may affect grade

Question 29

Preckel’s findings

Answer 29

After isolating the variable of chronotype, having an owl chronotype is a negative predictor of maths and language GPA

Question 30

Application to Preckel?

Answer 30

Start colleges and schools later so those with owl chronotype are not at a disadvantage

Question 31

Melatonin

Answer 31

Hormone secreted in pineal gland to induce sleep
Activated by exogenous cues: darkness, and when someone knows the time is late (time sense)

Question 32

Melatonin supplements

Answer 32

Provide boost of melatonin to go to feel sleepy (makes someone go to bed earlier)

Question 33

When should someone use melatonin supplements?

Answer 33

To go to bed earlier eg phase advance of their sleep-wake cycle

Question 34

How can melatonin in the Uk be obtained?

Answer 34

Only via prescription from a GP

Question 35

Light boxes

Answer 35

Artificial boxes of light that sitting in front of for 15 mins a day will keep someone awake for
Because it uses light as an exogenous cue to prevent pineal gland releasing melatonin

Question 36

When should someone use a light box?

Answer 36

To go to bed later eg phase delay of sleep wake cycle