Lesson 11 – Ultradian and Infradian Rhythms

Question 1

What is an ultradian rhythm?

Answer 1

Ultradian rhythms span a period of less than 24 hours

Question 2

What is an example of an ultradian rhythm?

Answer 2

The 5 sleep stages

Question 3

Describe the 5 sleep stages (example of ultradian rhythms)

Answer 3

Human sleep follows pattern alternating between Rapid 👁 Movement (REM) 💤 (stage 5) and Non-Rapid 👁 Movement (NREM) 💤 (stages 1, 2, 3 and 4)- cycle repeats itself every 90 min

Question 4

How do the stages of sleep vary?

Answer 4

Each stage shows a distinct EEG pattern
As person enters deep 💤- their brainwaves slow and breathing and ♥️ rate ⬇️
During 5th stage (REM sleep)- EEG pattern resembles that of awake person- during this stage dreaming occurs

Question 5

What is the basic rest activity cycle?

Answer 5

Kleitman (1969) referred to 90 min 🚲 found during 💤 as Basic Rest Activity Cycle (BRAC)
Suggested that 90 min 🚲 continues when awake- during day, rather than moving through 💤 stages- we progressively move from state of alertness into state of physiological fatigue
Studies suggest human mind can focus for about 90 min AND towards end body begins to run out of resources-> loss of concentration, fatigue and hunger

Question 6

What are the evaluation points of ultradian rhythms?

Answer 6

👍- research support for ultradian rhythms- Ericsson et al. (2006)- studied group of elite violinists 🎻 and found that group practise sessions limited to 90 min- violinists frequently napped to recover from practise with best violinists napping more
- same pattern found among athletics, chess players and writers … fits with BRAC
👎- individual differences- Tucker et al. (2007)- ultradian rhythms biologically determined and may even be genetic in origin
- pps were studied over 11 consecutive days ☀️ and nights 🌓 in lab 🧪 environment- researchers assessed 💤 duration, ⏰ taken to fall 💤 and amount of ⏰ in each 💤 stage- found differences in all characteristics

Question 7

What is an infradian rhythm?

Answer 7

Infradian rhythms- span period longer than 24 hours- may last weeks, months or even a year

Question 8

What is an example of an infradian rhythms?

Answer 8

Menstrual 🩸 cycle- lasts about a month- considerable variations in length of 🚲- some women experience 23 day 🚲 and others 36 day 🚲 (Refinetti, 2006) BUT average 28 days

Question 9

How is the menstrual cycle regulated?

Answer 9

Hormones regulate menstrual 🩸 cycle

• Ovulation occurs roughly halfway through 🩸 cycle when oestrogen levels peak and usually lasts for 16-32 hours
• After ovulation progesterone levels ⬆️ in preparation for possible implantation of embryo in uterus

Question 10

What are the evaluation points of infradian rhythms?

Answer 10

👍- Infradian rhythms can affect 🏃‍♂️- Penton-Voak (1999) found that women express preference for feminised male faces when choosing partner for long-term relationship BUT show preference for masculinised faces during ovulation
👎- menstrual 🩸 cycle ✖️ only governed by infradian rhythms- when several 👩 of childbearing age live together and ✖️take oral contraceptives their 🩸 cycles synchronise
- In 1 study samples of sweat 💦 collected from 1 group of 👩 and rubbed onto upper lip👄 of another group of 👩-> 🩸 cycles becoming synchronised- suggests synchronisation affected by pheromones (chemical substance produced and released into environment by 🦒 🦔 🦓 which affects 🏃‍♂️ of others of same species