Biological Rhythms Sleep And Dreaming

Updated 2009-06-04 12:38

Biological Rhythms

Research into circadian, infradian and ultradian rhythms

Siffre (1975)When spent 6 months in a cave, circadian rhythm extended to 25 hours.
Aschoff + Weaver (1976)Placed ppts in an underground bunker and found that most circadian rhythm lengthened to 24-25 hours, although some were as long as 29 hours.
Folkard (1985)When tried to reduce ppts circadian rhythm down to 22 hours, most people couldn’t get any lower than 23 hours.
Czeisler (1991)Could alter ppts circadian rhythms down to 22 and up to 28 hours with dim lightning.
Czeisler (1999)Huge individual differences occur - circadian rhythm can vary from 13-65 hours.
Folkard (1977)Temperature cycle - STM better in morning, LTM better in afternoon in 12-13 year olds.
Monk + Embrey (1981)Alertness is best when body temperature is lowest, in early morning and early evening.
Hawkins + Armstrong-Esther (1978)Circadian rhythms: Nurses doing shift work took longer to adjust their temperature rhythms than their sleep=wake cycle.
Russel (1980)Infradian rhythms: When sweat from one group of women rubbed onto lips of another group, 4 out of 5 menstrual cycles synchronised to within a day of the donor.
Reinberg (1967)Infradian rhythms: When a woman spent 3 months in a cave, her menstrual cycle decreased to 25.7 days.
Freidman + Fisher (1967)Ultradian rhythms: Observed a 90 minute cycle in terms of eating+drinking behaviour of psychiatric patients.

Research into Endogenous Pacemakers and Exogenous Zeitgebers

Darlington (1998)Endogenous pacemakers: Proteins CLOCK+CYCLE loop opposite with PER+TIM in our biological clock.
Decoursey (2000)Endogenous pacemakers: Destroyed SCN in chipmunks and found that circadian rhythms were disrupted.
Morgan (1995)Endogenous pacemakers: Bred mutant hamsters to have a 20 hour circadian rhythm, then transferred SCN into other hamsters, who also adopted the 20 hour rhythm.
Hall (2000)Exogenous zeitgebers: Other locations of the body besides the eyes contain proteins to detect changes in light.
Campbell + Murphy (1998)Exogenous zeitgebers: Shining light on back of ppts knees shifted circadian rhythms.
Miles (1977)Exogenous zeitgebers: Studied a blind man whose circadian rhythm was 24.9 hours.
Czeisler (1995)Exogenous zeitgebers: Found that some blind people do respond to very bright lights by inhibiting melatonin secretion.
Luce and Segal (1966)Against exogenous zeitgebers: People living within the Arctic Circle, where the sun never sets, still sleep for 7 hours.
Kelly (1991)Against exogenous zeitgebers: US submariners could not adjust to an 18 hour day despite social cues + lighting.

Research into disrupting biological rhythms

Knutsson (1986)Increased risk of heart disease after 18 years shift work.
Czeisler (1986)Bright light can be used to mimic effect of daylight to combat effects of shift work.
Recht (1995)Effect of jet lag: found that baseballers won more games when travelling East to West (phase delay)


Theories of Sleep

Webb (1982)Key study - Hibernation Theory. We sleep to conserve energy. Smaller animals sleep for longer as they have a higher metabolism that uses energy quickly.
Zepelin and Rechtschaffen (1974)Supports Hibernation Theory. Found that total sleep time correlated negatively with body size.
Meddis (1975)Predator Avoidance Theory - sleep evolved to keep animals safe when they are most vulnerable and prey species sleep less as tey need to be vigilant.
Aliison and Ciccheti (1976)Supports Predator Avoidance - found that sleep correlates negatively with level of danger typically faced.
Oswald's Restoration TheoryREM sleep is important for brain growth+repair.
Horne (1988)Expands on Restoration Theory. There is core sleep and optional sleep. We do not sleep to restore the body.
Rechtschaffen (1993)Supports Restoration Theory. 'Rotating rats' study found that all rats died within 33 days.
Jouvet (1967)Flower pot technique to deprive cats of REM - became disturbed and died on average after 35 days.
Lavie (1984)Challenges Restoration theory. Experienced no REM sleep for 13 years with no long term effects.


Nature of dreams

Kahn (2000)Content: 1/2 known to dreamer, 1/3 generic characters, 1/6 unknown.
Hobson (2000)Content: PET scans show emotional region of brain more active during REM sleep.
Martin (2002)Content: gender differences - males dream of other males more than females dream of males.
Cartwright (1984)Content: Found that for ppts going through separation or divorce, dream content correlated with how they coped whilst awake.
Domhoff (2002)Content: culture differences. MexicanAmerican dreams were higher on emotions and good/bad fortune than AngloAmerican.
Horne (1999)Duration: Dreams run in 'real time', some lasting over 30 minutes.
Dement + Kleitman (1957) (Duration)Duration: Number of words used to describe the dream correlated with length of REM activity.
Dement + Kleitman (1957) (Kinds of dream)Kinds of dream: 80% reported dreams when stopped during REM compared to 7% for NREM.
Martin (2002)Hyponagogic and hypnopompic dreams are reduced versions of normal dreaming experienced when falling alseep/waking up.

Theories of dreaming

Crick + Mitchison (1983)Reverse learning theory. Dreams are meaningless. The brain has a limited capacity and we dream to get rid of useless cognitive debris, which if remained can cause obsessive/paranoid behaviour.
Goertzel (1977)Supports Reverse Learning TheoryBrain can only store 100 thousand billion 'bits' of information.
Freud's psychosocial theory of dreamingDreams are the fulfilment of wishes/desires of the id that could not be satisfied in the concious mind. Latent content = real meaning, manifest content = what we see. Process between the two = dreamwork.
Solms (2000)Supports Freud, challenges reverse learning. Found that dreams activated by forebrain (meaning+motivation) rater than brainstem.
Braun (1991)Challenges Freud. How is dreamwork possible if rational part of the brain is inactive? (as dreamwork would require high level processing)