Weed and Fatigue: How THC Messes With Your REM and Deep Sleep

Weed can make you tired because THC changes how your sleep is built: research suggests it shortens REM sleep and stretches out deep sleep, and many people feel drowsy and sluggish after smoking. Plenty of regular users have felt that heavy, sleepy fog at some point, but it varies a lot from person to person and depends on several factors.

Besides leaving some people a little dopey, it's no secret that a lot of cannabis users rely on it to fall asleep. Still, weed can affect each stage of sleep in different ways.

That said, some people get a lot more out of cannabis as a sleep aid than others.

How Does the Human Sleep Cycle Work?

Human sleep happens in cycles, and each cycle moves through four stages:

• Stage 1: the in-between zone, half asleep and half awake. You can be woken up easily here.
• Stage 2: light sleep, which is a bit harder to wake up from.
• Stage 3: deep sleep, also called slow-wave sleep.
• Stage 4: REM (rapid eye movement) sleep, the stage where most vivid dreaming happens.

How Does Cannabis Affect Sleep?

Several studies have found that THC reduces the length and intensity of REM sleep, while it may increase the time spent in deep sleep.

Study 1

A 1975 study on THC and sleep patterns found that taking 210 mg of THC a day for two weeks significantly reduced eye movement during REM sleep.

It also slightly shortened the time sleepers spent in REM. Finally, the study found that deep sleep got a little longer after taking THC.

Study 2

Later, a 2008 clinical review again found that small amounts of cannabis can increase deep sleep, which may help users fall asleep more easily. It also showed that cannabis use can lower total REM sleep and REM density.

Higher doses, on the other hand, can have the opposite effect and lead to:

• Less REM sleep
• Less slow-wave sleep
• A shorter time between being wide awake and falling asleep
• Hallucinogenic effects

Study 3

Finally, a 2015 review found that chronic use has mixed effects: people can build up a tolerance to its effect on how fast they fall asleep (sleep latency), for example, but not so much to its effects on REM sleep.

Should You Worry That Weed Makes You Sleepy?

If weed makes you sleep a lot, it's usually nothing to panic about. But if you feel it's dragging down your day-to-day life, it's a good idea to take a tolerance break.

Possible Risks of Smoking Weed Right Before Bed

Within a few minutes of inhaling cannabis smoke, your heart rate starts to climb, your airways relax and open up, and the blood vessels in your eyes dilate, which is why your eyes get red.

If you check your heart rate before smoking, it's usually somewhere around 70 to 80 beats per minute. After smoking, it can go up by 20 to 50 beats per minute, or even double, depending on the person.

Timing matters too: some data suggest the risk of a heart attack in the first hour after smoking weed is nearly five times higher than your baseline risk. That may be partly because cannabis raises blood pressure and heart rate and lowers the blood's ability to carry oxygen.

Weed can also cause orthostatic hypotension (dizziness or lightheadedness when you stand up), which can raise the risk of fainting and falls.

Weed and Sleep: A Few Tips

If you don't want to feel wiped out, the single most important move is taking a break. A T-break can also help you reset your relationship with weed and cut down that fatigue. Other options are trying different strains and exploring alternatives.

Another tip is to fight the drowsiness with CBD, which may soften some of THC's effects.

Weed Strains That Make You Sleepy

Here are a few strains that people love for heading straight to bed and sinking into the knockout sleep you've been chasing after too many sleepless nights. The old indica vs. sativa split doesn't help much here; it generalizes too much to be useful.

So here's a top five of strains that can make you sleepy, and that you're better off skipping if you need to stay awake:

• Northern Lights.
• Royal Jack Automatic.
• Legendary OG Punch.
• Sweet ZZ.
• Medical Mass.