Meanwhile, a 34-year-old veteran, who has completed two tours, battles persistent sleep issues upon returning home. Falling asleep takes him two hours, only to be abruptly awakened by nightmares. For months, he hasn’t managed more than three hours of rest per night, and the toll is evident. With a friend vouching for cannabis and facing a six-month wait for a sleep specialist at the Veteran’s Affairs medical center, alongside a nearby dispensary open until late, the choice seems straightforward.
Both will tell you cannabis works for their specific needs. They are not entirely wrong. But no one has told them what is actually happening inside the brain when the lights go out. It’s complex, and for them – as for many others – ultimately it’s a trap.
As a neurologist specializing in sleep and brain performance, I write this not as someone opposed to cannabis but as someone who regularly sees patients whose sleep has quietly unraveled after months or years of use, especially teenagers and veterans.
I believe the public deserves a more complete picture than they currently have due to the limited research that’s available.
Why the teenage brain is especially vulnerable
From the early teens through the mid-20s, the brain is actively under construction, clearing out weak or redundant connections and reinforcing the circuits responsible for judgment, emotional regulation and stress response.
Tetrahydrocannabinol, or THC, the psychoactive component of cannabis, interferes with this process directly by acting on the endocannabinoid system, one of the primary regulatory networks guiding it.
A 2021 brain imaging study of 799 teenagers found that cannabis use was associated with dose-dependent thinning of the cerebral cortex – meaning the more cannabis a teenager used, the thinner their prefrontal cortex became. The prefrontal cortex is the region of the brain responsible for judgment, decision-making and impulse control. Thinning of the cortex in this region has been associated with increased impulsivity, poorer decision-making and reduced inhibitory control.
Another seldom-discussed factor is how puberty affects sleep. Hormonal changes and brain maturation in adolescence shift the internal biological clock, known as the circadian rhythm, toward a later sleep schedule.
And teenagers are far from alone. A 2025 study found that more than 1 in 5 young adults in the U.S. turn to cannabis or alcohol to fall asleep. For teenagers who are already sleep-deprived and facing early school start times, cannabis can become its own nightly fix.
What cannabis is doing while you sleep
Sleep is not passive. It is well-organized, purposeful and foundational to our physical and brain health.
Every night, the brain cycles through distinct stages, each serving a specific function. All sleep stages matter, but the one that matters most is REM sleep, the dreaming stage. This is when the brain processes the emotional weight of the day, locks in learning and resets the brain circuits that govern mood, judgment and resilience.
THC has a sedative effect at low doses but is stimulating at high doses. Cannabis also contains other cannabinoids – plant-derived compounds such as CBD and CBN that interact with a system in the body that produces its own cannabinoids and contributes to the sedative effects of cannabis.
Here is where it gets complicated.
THC does help people fall asleep faster, but that effect fades quickly as the body adapts to regular use. The same gummy that once helped someone fall asleep quickly does less. They need more to get the same effect.
In addition, falling asleep quicker is not the same as sleeping well. A 2025 review of the research to date found that cannabis does not consistently improve sleep overall, including how long people stay asleep or how restful that sleep is.
In a separate study, chronic daily users spent significantly more time awake during the night and got less restful sleep compared with nonusers; another study found that using cannabis close to bedtime had similar effects.
In other words, the subjective sense of sleeping better does not match what the brain recordings show.
When relief becomes reliance
At this point many people are using cannabis not because it is working well, but because stopping feels worse.
Even when chronic cannabis users have the willpower to stop, they often face brutal withdrawal symptoms that are more severe than what drove them to cannabis in the first place. Sleep disturbance, including insomnia and disturbing dreams, is described as a common manifestation of cannabis withdrawal. In addition, two-thirds of users report other symptoms such as anxiety, depressed mood, restlessness, irritability, decreased appetite or a combination of these symptoms that often persist for weeks after stopping use.
The discomfort of withdrawal drives many people to keep using it.
This is the trap – it’s quiet and insidious, which makes it harder to see.
Cannabis works just enough to feel like a solution. Night after night it dulls the problem without fixing it, until stopping feels unthinkable. When someone finally tries to quit, their sleep falls apart. So they go back. The original reason they could not sleep has not been identified or treated, and it hasn’t gone away.
Trying to quit cannabis use can bring about severe withdrawal and other symptoms. Jamie Grill/Tetra Images via Getty Images Veterans and the need for long-term recovery
The developing brain is one kind of vulnerability. The traumatized brain is another.
Post-traumatic stress disorder affects an estimated 12% to 23% of post-9/11 veterans, compared with 6% to 8% of the general population. Sleep disturbances affect 70% to 90% of military personnel with PTSD. People with PTSD commonly have nightmares that are visceral, relentless and exhausting. They might be jolted awake with a pounding heart, multiple times a night, for years.
As a result, many veterans turn to cannabis to help them sleep. It’s understandable, especially when it can take weeks or months to get an appointment with a mental health practitioner.
But the data on outcomes for veterans is sobering. Those with cannabis use disorder – meaning cannabis use they struggle to control despite negative consequences, which affects roughly 1 in 4 veterans who use cannabis nonmedically – have higher rates of depression, anxiety and suicidal ideation and respond much more poorly to evidence-based PTSD treatments.
Because these withdrawal symptoms so closely mirror PTSD itself, many veterans interpret the return of symptoms as their condition worsening, not as withdrawal, so they go back to cannabis. And the cycle continues.
What actually works, and why it’s so hard to get
Cognitive behavioral therapy for insomnia, or CBT-I, is considered the first-line treatment for persistent insomnia. Research shows that it outperforms every sleep medication, cannabis included.
This therapy works by modifying sleep habits, regulating sleep-wake schedules, reducing arousal and reframing unhelpful beliefs about sleep. A form of treatment known as image rehearsal therapy, in which patients rewrite the storyline of a recurring nightmare and mentally rehearse the new version while awake, has been shown to be effective for veterans with trauma-related nightmares. But trained CBT-I providers are scarce, wait times are long, and most primary care settings do not offer it.
In other words, the people most vulnerable to the sleep-related harms of cannabis use are the least likely to have access to treatments that address the underlying problem, and the most likely to get caught in a negative cycle.
For those already caught in that cycle, quitting abruptly rarely works and often makes things worse. Research shows that CBT-I can reduce both insomnia and cannabis use at the same time – treating the root problem so cannabis no longer feels necessary.
Sleep is the foundation on which memory, mood, judgment and recovery are built.
The 15-year-old who cannot fall asleep and the veteran who wakes gasping at 3 a.m. both deserve evidence-based information about what is happening in their brains, and real access to care that treats the root cause.
