Why does your brain feel so useless after a late night or a sleepless night? Researchers know that our entire body rests and recharges during the night but the effects on the brain go far deeper. The stark effect on our moods plays a huge role in our overall health.

To find out more, a team of researchers from the Center for Human Sleep Science in the Department of Psychology, University of California, Berkeley, tested anxiety levels of study participants after a good night’s sleep and after a night where they were kept awake. Next, they tracked their brain activity as they watched emotion-inducing videos, such as seeing other people crying.

In the resulting research paper, Overanxious and Underslept, the researchers reported “even modest night-to-night reductions in sleep across the population predict consequential day-to-day increases in anxiety.” They traced the physical changes within the brain and how they affect how edgy you feel, depending in part on how rested you are.

It has long been known that lack of sleep and rising levels of anxiety and other mental disorders are interrelated. People who have psychotic breaks usually report a prolonged period of insomnia before they crash, but the effects of sleeplessness have an impact on anyone fighting back against the onset or escalation of anxiety or depression.

The Berkley study notes it contributes “to an emerging framework explaining the intimate link between sleep and anxiety and further highlights the prospect of non-rapid eye movement sleep as a therapeutic target for meaningfully reducing anxiety…Finally, we examine what it is about sleep, physiologically, that provides such an overnight anxiety-reduction benefit.”

It turns out there is a close relationship between how long people sleep and how they experience the world. The longer people go without sleep, the more distressed they begin to feel. Sleep disturbances are also a common symptom of major mood disorders such as depression. Improving sleep quality is an early target for many approaches to therapy because when people sleep better, they feel better.

As you likely know from experience, you tend to feel more uneasy if you haven’t slept well. There is a biological explanation for that. The Berkley brain scanner found that study participants’ medial prefrontal cortexes were less able to control their emotions – one of its primary jobs – when a person had not slept, particularly when it was exposed to tear-jerking videos. 

This part of the brain also affects decision making, so there may be consequences on how you make life choices if you are not in top form. It also works closely with other parts of the brain that release feel-good hormones, such as dopamine and serotonin.

Meanwhile, the amygdala part of the brain was more likely to respond to emotions after being deprived of sleep. It processes your emotions, including fear and your body’s response to perceived threats.

In short, the gateway to your anxiety is less guarded and your reactions to stimuli become more elevated, making you even more anxious.

While deep rapid-eye-movement (REM) sleep has long been touted for its healing effects, the Berkley study says the “non-rapid eye movement (NREM) slow-wave oscillations offer an ameliorating, anxiolytic [anxiety-reducing] benefit on these brain networks following sleep.” That stage occurs right after you fall into a deep sleep.

The more of this type of sleep participants had, the better able they coped in the face of anxiety in the morning.

Clearly, insomnia and anxiety feed each other in unhealthy ways. Therefore, it is vital to break the cycle as soon as it begins. That means scheduling regular sleep, whether you’ve had a stressful day or not. Getting into a routine will help you on the days when you are jittery or distressed. 

By resting your brain, you help it to restore its capability to support you and your reactions to the world around you. If your emotion-processing center can do a better job, then you can cope better without getting caught up in unnecessary drama. You will also only respond to true threats and not waste energy on red herrings. 

With good sleep, you can focus on looking ahead, rather than worrying about things that you cannot control. And by reining in your sleep habits, you gain more power over your life.

References: https://elemental.medium.com/why-a-lack-of-sleep-makes-you-anxious-e5ba2ed699a1

Overanxious and underslept, https://www.nature.com/articles/s41562-019-0754-8