For those sick of unwelcome nighttime visits from their subconscious, getting rid of bad dreams can now be done with the flick of a switch. Neuroscientists at the University of Berkeley, California, found that a switch could be implanted into the brains of mice which, when flipped, could activate or deactivate the neurons responsible for our dreams.
Researchers found that when an optogenetic switch was inserted into a group of nerve cells in the medulla (located in the hindbrain) a laser light could induce rapid eye movement (REM) sleep. This particular form of shut-eye, which accounts for around a quarter of sleep time in adults, sees random side-to-side eye movements in which the cortex is activated and the skeletal muscles paralyzed when the eyes are closed, causing those in its throes to dream.
By targeting the neurons in question, mice’s ability to enter REM could be controlled. “People used to think that this region of the medulla was only involved in the paralysis of skeletal muscles during REM sleep,” explained the study’s lead author Yang Dan. “What we showed is that these neurons triggered all aspects of REM sleep, including muscle paralysis and the typical cortical activation that makes the brain look more awake than in non-REM sleep.”
“Because of the strong induction of REM sleep—in 94 percent of the recorded trials our mice entered REM sleep within seconds of activating the neurons—we think this might be a critical node of a relatively small network that makes the decision whether you go into dream sleep or not,” Dan continued.
The paper’s researchers believe that their findings will lead to investigations into why we dream at all.
“Many psychiatric disorders, especially mood disorders, are correlated with changes in REM sleep, and some widely used drugs affect REM sleep, so it seems to be a sensitive indicator of mental and emotional health,” said Franz Weber, its first author. “We are hoping that studying the sleep circuit might lead us to new insights into these disorders as well as neurological diseases that affect sleep, like Parkinson’s and Alzheimer’s diseases.”
While the research yields a great deal of opportunity for further medical progression, it remains to be seen whether the optogenetic switch might become an option for those afflicted by their subconscious. Though dreams being plagued by the likes of deceased relatives and ex-partners may be painful, to shut ourselves off from those nighttime thoughts completely may prove to be unwise.
“Remembering negative moments from the past is something we shouldn’t cut ourselves off from,” says Stephen, 24. “Though it can be difficult in the short-run to recall such things, those kinds of dreams can allow for reflection and serve as a reminder of what we have now.”
“By the same token, dreams can stir amazing memories, too, which can prompt things like rekindling old friendships. That kind of influence can be really important,” he adds.
There are also many health benefits to dreaming, particularly for those with depression. A study from the early 90s pinpointed that divorced women who could recall their dreams—some of which involved ex-spouses—were in better moods upon waking, and had a far greater likelihood of recovering from depression than those who either did not dream about their former partners or couldn’t recall what they had dreamt of.
It’s studies like these that informed a later paper from the Centre for Cognitive Neuroscience, which centered around the hypothesis that dreaming is a biological process designed to simulate threatening life events, through which perception and avoidance can be rehearsed.
“For every negative dream, there are usually so many more in which you can navigate challenging circumstances before they actually happen,” Stephen agrees. “The value of that shouldn’t be dismissed.”