stages of sleep

• An example is the sleep cycle.
• An Ultradian rhythm is a biological rhythm, with a frequency of more than one cycle in 24 hours
• The sleep cycle is a cycle of about 90 minutes,

  which repeats itself throughout the night-time.
• • The stages of sleep in the sleep cycle is an ultradian rhythm.
• 5 distinct stages of sleep have been identified that altogether

  last around 90 minutes. This cycle that continues throughout the course of the night
• Each stage is characterised by a different level of brainwave

  activity that can be monitored using an EEG.
• Stage 1

  NREM Sleep

  5 - 1 0 m i n u t e s

  • Very light sleep

  • Eyes closed

  • Can easily b e

  a w o k e n

  • Muscle activity

  S l o w s

  • May have the

  s e n s a t i o n o f

  falling
• Stage 2

  NREM S/eep

  2 0 m i n u t e s

  • Light sleep

  • Body

  t e m p e r a t u r e

  drops

  • H e a r t r a t e s l o w s

  • Body gets ready

  for d e e p e r

  s l e e p
• Stage 3

  NREM Sleep

  T r a n s i t i o n t o

  Deep Sleep

  • Extremely slow

  b r a i n w a v e s

  interspersed

  with smaller,

  f a s t e r w a v e s
• Stage 4

  NREM S l e e p

  3 0 m i n u t e s

  • Deep sleep

  phase

  • Difficult to wake

  you

  • Body has very

  little m o v e m e n t

  • Repairs and

  rejuvenates

  muscles, bones,

  a n d t i s s u e
• Stage 5

  REM S/eep

  1 0 m i n u t e s - 6 0 m i n u t e s

  • Deepest sleep

  p h a s e

  • Rapid, shallow

  breathing

  • M u s c l e s a r e

  t e m p o r a r i l y

  paralyzed

  • W h e n m o s t

  dreams occur