No Acute Effects of Cannabidiol on the Sleep-Wake Cycle of Healthy Subjects: A Randomized, Double-Blind, Placebo-Controlled, Crossover Study

Cannabidiol (CBD) is a component of the plant cannabis with various therapeutic benefits including antidepressant and anxiolytic (anxiety-relieving). Despite being a known regulator of brain functions (hence its benefits against the above neuropsychiatric conditions), not much is known about the possible interference of CBD on the sleep-wake cycle. For its medical applications to be safe, understanding such potential effects is crucial.
To evaluate how CBD influences the sleep-wake cycle of healthy adults, researchers at the Florey Institute of Neuroscience and Mental Health, Australia conducted a study on 27 healthy volunteers. The volunteers were allocated to receive either CBD or placebo in the first night; in the second night, the same procedure was performed using the substance that had not been administered in the previous session. During both nights, following the administration of CBD or placebo, a sleep study which records one’s brain waves, blood oxygen level, heart rate and breathing, eye and leg movements was conducted on the sleeping volunteers. The next morning, immediately after the sleep study, cognitive and subjective measures were also performed to assess possible residual effects of CBD. 
Data from this study suggested that CBD neither altered any indexes of sleeping quality nor interfere with different phases of the normal sleep cycle significantly. Furthermore, CBD did not leave any negative impacts on the cognitive or motor functions of the participants the following morning. This is starkly different from common anxiolytic and antidepressant drugs such as benzodiazepines and selective serotonin reuptake inhibitors, which are known to have adverse side effects on sleep.

read the study here