Sleep is a vital biological process, serving an important role in proper neurodevelopment, energy conservation, brain waste clearance, modulation of immune responses, neurocognition, mood, memory consolidation and performance/vigilance. Many of these processes are altered in psychiatric illnesses. There is mounting evidence that the endocannabinoid system (ECS) plays a key role in the sleep/wake cycle. Acute administration and chronic use of THC and cannabis have been shown to alter sleep in small studies of healthy, young people. Sleep disturbances are also part of cannabis withdrawal syndrome and include increased sleep complaints, decreased SWS and increased REM. Sleep disturbances are a promising target for treatment of cannabis use disorder. Given the link between cannabinoids and psychosis, the role of cannabis-induced sleep alterations in psychosis-prone individuals and schizophrenia patients warrants further study.

The normal EEG doesn’t change much during adult life, but it must be interpreted in the context of physiological states (awake, drowsy, or asleep). Normal wakefulness is characterized by a reactive posterior dominant alpha rhythm, anterior faster beta activity, eye blink, and muscle artifact. Transition to drowsiness is typically characterized by attenuation of the posterior dominant rhythm, diffuse slowing into theta range, emergence of slow lateral eye movements, and dissipation of muscle artifact. Vertex waves are the architectural feature of stage I sleep. Positive Occipital Sharp Transients of Sleep (POSTS) may also occur. Sleep spindles and K complexes are the architectural feature of stage II sleep. Mitten waves are a normal variant, while dyshormia is abnormal. Slow wave sleep is characterized by diffuse high-amplitude semi-rhythmic delta slowing. Rapid eye movement sleep is characterized by eye movement artifact and sawtooth waves.