22.214.171.124.1.1 3) Lasts 15 mins. EEG activity is characterised
by long slow- delta waves with sleep spindles.
126.96.36.199.1.1.1 4) Lasts 30 mins approx. Slow - wave sleep- long slow waves
of EEG. The EOG & EMG show very little activity.
188.8.131.52.184.108.40.206 5) Lasts approx 10 mins- first cycle -builds up to an
hour by 4th/5th cycle. EEG activity is characterised by
beta waves- relaxed waking state linked to dreaming.
2 Circadian Rhythm
2.1 Lasts about 24 hours e.g. Sleep wake cycle, Body temp
2.2 1) Humans and mammals have an
endogenous pacemakers - internal
biological - suprachiasmatic nucleus
(SCN) -lies in the hypothalamus -lies
above optic nerve.
2.2.1 2) SCN sends signals to pineal
gland-increase production melatonin at
night- Melatonin induces sleep
inhibiting brain mechanisms that
3 Infradian Rhythm
3.1 Occurs for a period more than one
day but less than one year e.g. Female
Menstrual Cycle- lasts approx 28 days
3.1.1 Female Menstrual Cycle (AO1)
220.127.116.11 Driven by fluctuating hormone
levels. Research suggests - pituitary
gland releases hormones which
stimulate follicle in 1 ovary to ripen
egg- release oestrogen
3.1.2 SAD (AO1)
18.104.22.168 Infradian rhythms do not have to
monthly- can occur once a yr. SAD can
occur e.g. during winter months and
people recover in the summer.
22.214.171.124.1 Research shows- melatonin secreted -pineal gland =
dark ; more darkness - the more melatonin. Research
also shown- melatonin related to chronic depression.
But SAD may be due- disruption to circadian rhythm
e.g. go to bed earlier wake up later in dark
4 Circannual Rhythm
4.1 Occurs or fluctuates at
intervals of approx one year
e.g. Migration of birds
5 What controls Biological Rhythms?
5.1 Endogenous Pacemakers- Regulate your rhythms inside your body
5.2 Exogenous Zeitgebers- Regulate your behaviour outside your body
6 Disruption of biological rhythms
6.1 Shift Work
6.1.1 - Decreased alertness - sleep deprivation -
effects on health
6.2 Jet Lag
6.2.1 Erroneous decision making - hard to
make decisions due to jet lag.
6.2.2 Less difficulty - travelling east to west (phase delay)
6.2.3 More difficulty to adjust West to East (Phase Advance)
6.3 Real life applications: IDA
6.3.1 Chernobyl, Exxon Valdez oil tanker grounding, space shuttle challenger