Insomnia and cognitive behavioural therapy—how to assess your patient and why it should be a standard part of care

Normal sleep relies upon two distinct but overlapping neuronal circuits. The homeostat drives an increasing pressure to sleep after every hour awake and the circadian rhythm drives alertness in the day and sleep at night with light intensity as the strongest external timekeeper (1). Both total sleep time and the circadian rhythm change over the course of our lives and tend to fragment and weaken over time (2). Teenagers and young adults need 8–9 hours of sleep on average with a delay in sleep phase such that many fall asleep after rather than before midnight (3). There is phase advance (i.e., falling asleep earlier) with every decade that passes with adults falling asleep by 30 minutes earlier a decade on average from the third decade onwards. There is increasing sleep fragmentation and increased time to fall asleep in otherwise healthy older adults with and without sleep complaints (4)