Biopsychology(circadian rhythms)

Question 1

Circadian rhythm basic definition -

Answer 1

Refer to a pattern of behaviour that occurs or reoccurs about every 24 hours, which is set and reset by environmental light levels.

Question 2

Nature of circadian rhythms -

Answer 2

Light sensitive cells within the eye act as brightness detectors, send these messages which have been received from the environment to the SCN.
SCN coordinate the entire activity circadian system. Most likely the sleep-wake cycle.

Question 3

Sleep-wake cycle basic definition -

Answer 3

Refers to the alternating states of sleeping and waking that are dependent on the 24-hour cycle.

Question 4

Sleep wake cycle nature

Answer 4

-Dictates not only when we should be sleeping but also when we should be awake.
-Light and darkness are external features.
-So drops at different times of the day
-Strongest sleep drive occurs between 2-4 am and 1-3 pm
-The sleepiness experienced in these dips may be due to sufficient sleep or deprived sleep.

Question 5

External features?

Answer 5

Sensitivity of light and darkness, so drops at different times of the day.

Question 6

Strongest sleep drive occurs at what times?

Answer 6

2-4 am and 1-3pm, the sleep experienced may determine how we feel during the sleep-wake cycle for example if we are sleep deprived or sleep sufficient.

Question 7

Other factors influencing the circadian rhythm

Answer 7

Core body temperature and hormone production.

Question 8

Core body temperature as a circadian rhythm

Answer 8

Influences circadian rhythm.

Question 9

Core body temperature lowest?

Answer 9

36 degrees at about 4.30 am

Question 10

Core body temperature highest?

Answer 10

38 degrees at about 6pm

Question 11

How does core body temperature influence sleep?

Answer 11

Sleep begins to occur during the circadian rhythm when the core body temperature begins to drop. Whereas when the body temperature begins to rise this promotes a feeling of wakefulness.

Question 12

Hormone production in circadian rhythms?

Answer 12

Hormone release impacts circadian rhythms, the production of melatonin from the pineal gland in the brain.

Question 13

Melatonin peaks at what time of day?

Answer 13

Peak levels are reached during the hours of darkness.

Question 14

Why is melatonin peaked at this time?

Answer 14

Peaked at darkness levels due to activation of chemical receptors in brain. This hormone promotes the feeling of sleep.

Question 15

When is melatonin production from the pineal gland reduced?

Answer 15

Hormone production drops during the hours of daylight and when a person wakes.

Question 16

Temperature may be important than light in regulating a circadian rhythm.

Answer 16

Buhr believes that are circadian rhythms (body clock) are controlled by temperature not light. Although light may trigger the SCN. The SCN uses information from light that may be used in neural activity to change body temperature. Body temperature fluctuate on a 24-hour cycle and even the smallest drop in changes can send powerful signals to body clocks. He found that these fluctuations set timing of the cells in the body. This suggest that temperature may be important than light.

Question 17

Research support of the importance of light in setting a circadian rhythm

Answer 17

Hughes tested the circadian hormone release in 4 participants in the British Antarctic station.
At the end of the Artic summer (February) Cortisol levels followed a familiar pattern, which reached highest point at when the individuals woke. Lowest when going to bed.
After three months, of continuous darkness their pattern had changed, with the peak levels of cortisol now being at noon rather than them just waking. This therefore suggests that the difference of photoentrainment factors of light may be responsible for circadian hormone release promoting wakefulness.

Question 18

When is cortisol highest and lowest?

Answer 18

Highest when waking and lowest when sleeping.