By Pat Anson, PNN Editor

Getting a good night’s sleep can be a godsend to someone suffering from chronic pain. That’s why many pain patients are experimenting with medical cannabis to help manage their sleep problems.

But a small new study found that while cannabis initially helps with sleep, regular use leads to drug tolerance that causes even more sleep problems. A second study raises doubts about the use of cannabinoids in treating cancer pain.

Researchers at the Rambam Institute for Pain Medicine in Israel enrolled 129 volunteers over age 50 with chronic neuropathic pain. About half used medical cannabis for at least a year, either by smoking (69%), oil extracts (21%) or vaporizers (20%). The other half did not use cannabis.

Sleep problems were common among both groups of patients, with about 3 out 4 having trouble falling asleep or staying asleep.

Researchers found that cannabis users were less likely to wake up during the night, compared to those who did not use the drug. But over time the benefits of cannabis were reversed, and frequent users found it harder to fall asleep and woke up more often during the night.

The findings are published in the British Medical Journal's Supportive and Palliative Care journal.

“This study is among the first to test the link between whole plant MC (medical cannabis) use and sleep quality. In our sample of older (50+ years) chronic pain patients we found that MC may be related to fewer awakenings at night. Yet patients may also develop tolerance to the sleep-aid characteristics of MC,” researchers wrote.

“These findings may have large public health impacts considering the ageing of the population, the relatively high prevalence of sleep problems in this population along with increasing use of MC.”

The study was observational and did not establish a direct causal link between cannabis and sleep.  Another weakness is that the specific timing of cannabis use by participants was unknown. Taking cannabis before bedtime may have a stronger association with sleep. The researchers said their findings were preliminary and more larger studies were needed.

Cannabinoids Not Recommended for Cancer Pain

Another study published in the same medical journal found that cannabinoids do not reduce pain in patients with advanced cancer.

Researchers at the University of Hull in the UK reviewed data from five high-quality clinical studies involving 1,442 cancer patients and found that pain intensity was no different between those taking cannabinoids and those given a placebo.

Patients using cannabinoids also had nearly twice the risk of short-term side effects such as dizziness, drowsiness, nausea and fatigue. They were also more likely to drop out of studies.  

“For a medication to be useful, there needs to be a net overall benefit, with the positive effects (analgesia) outweighing adverse effects. None of the included phase III studies show benefit of cannabinoids,” researchers concluded.

“When statistically pooled, there was no decrease in pain score from cannabinoids. There are, however, significant adverse effects and dropouts reported from cannabinoids. Based on evidence with a low risk of bias, cannabinoids cannot be recommended for the treatment of cancer-related pain.”

The American Cancer Society takes a different view, pointing out that studies have found marijuana smoking can be helpful in treating nausea from cancer chemotherapy.  Other studies have also suggested that THC, CBD and other cannabinoids slow the growth of cancer cells in a laboratory setting.

Medical marijuana is legal in 33 In U.S. states and cancer is recognized as a qualifying condition in many of them.