Clinic Locations

Woolcock Sleep Clinic
Phone: (02) 9114 0000
Address: 431 Glebe Point Road, Glebe, NSW, 2037 Email: [email protected]
Royal Prince Alfred Hospital
Phone: (02) 9515 6655
Address: Level 11, Main Block, Missenden Road, Camperdown, NSW, 2050
Integrated Sleep Health
Phone: (02) 9331 7546
Address: Suite 1, Level 7, 26 College Street, Darlinghurst, NSW, 2010 Email: [email protected]

Professor Ron Grunstein AM

Professor of Sleep Medicine


Circadian Rhythm Sleep Disorders

Circadian Rhythm Sleep Disorders are a family of sleep disorders affecting the timing of sleep, characterised by an inability to sleep and/or wake at normal or appropriate times due to the dictates of the individual’s biological or circadian clock.

As a result, sleep is attempted (or actually occurs) at an abnormal time in the individual’s circadian cycle.

People with circadian rhythm sleep disorders are therefore unable to sleep and wake at the times required for normal work, school, and social needs, which can severely impact their quality of life.

The spectrum of CRSD includes:

  • Advanced Sleep Phase
  • Delayed Sleep Phase
  • Irregular Sleep-Wake Pattern
Circadian rhythm sleep disorders (CRSD)

Circadian rhythm sleep disorders arise due to phase shifts in individual circadian clocks.

Delayed sleep phase syndrome is when people cannot fall asleep till late often the early morning and then cannot wake up till late, missing work or school. We are involved in a national NHMRC funded study investigating the role of melatonin in such patients and work in our inter-disciplinary clinic managing this common problem.

As well it is well known that some patients with severe mental illness such as schizophrenia have very disorganised sleep time and often sleep during the day. In collaboration with other Sydney Local Health District researchers, we hope to understand the circadian rhythm and other sleep disorders (such as sleep apnea) impacting on patients with severe mental illness.