Ever felt irritable or depressed after not getting enough sleep? Here’s why

I’ve recently noticed that on days when I haven’t had a good night of rest, I feel more depressed and anxious. Negative thoughts overwhelm me, and I feel crabby and unable to do anything productive. Even the most basic tasks, such as taking out the trash and going to the grocery store, can seem inconceivable, and it feels impossible to pull myself out of the funk. That is, until I get some real rest.

According to psychotherapist Ellen Yom, lack of sleep can deeply influence our mental health and impact energy levels and motivation, decreasing our ability to cope with stress. Moreover, it can also make us more irritable and cause persistent sadness or moodiness.

Lack of sleep can cause lethargy, too, making us less likely to engage in social interactions, exercise, and other activities that actually boost our mood and provide us with a sense of connection, pleasure, or accomplishment.

As New York-based psychotherapist Allison Lewin explained to Hello Giggles,

"The decrease in social interaction and follow through with pleasurable or purpose-driven activities increases negative thoughts and beliefs about ourselves, our lives, and our future, and these thoughts contribute to feelings associated with depression and anxiety."

From a neurological standpoint, Lewin said that a lack of sleep can affect multiple parts of the brain, including our prefrontal cortex, which is in charge of reasoning and decision making: “Whereas the well-rested version of yourself is ideally capable of making sense of interactions and experiences in helpful ways, the sleep-deprived version with an affected prefrontal cortex may perceive experiences in different ways that elicit exaggerated feelings of sadness, hopelessness, guilt, shame, and fear characterized by depression or anxiety.”

It can also impact the amygdala, the area of the brain in charge of one’s fear response; lack of sleep causes the amygdala to become more active, which triggers an increase in cortisol levels. In turn, that triggers our fight-or-flight response and stirs up anxious feelings. 

Good quality sleep is powerful medicine, for both the body and mind. And this is especially true if you suffer from a mental health condition. Psychiatrist Carlene MacMillan said that without high-quality sleep, even the best treatment will be ineffective. “Life is going to be experienced through an unfocused lens, essentially,” she said. For illnesses such as bipolar disorder, all-nighters can lead to further episodes of mania or depression, while sleep and mood disorders are intricately linked. 

That’s why prioritizing sleep when you have a mental illness is so important. “Lack of sleep can amplify pre-existing mood and anxiety disorders through increased emotional volatility, irritability, and fatigue,” said Lewin.

While insomnia can trigger symptoms of your mental illness — when I was in the midst of a major depressive episode, for example, I would wake up hours before I had to get up, which is a symptom of the disorder — it can also be the cause of what seems like a health condition but isn’t.

“One example is that I see many people complaining they cannot pay attention in school or at work seeking treatment for ADHD. Sometimes that is the correct diagnosis. However, many times I find their sleep is of poor quality. It is impossible to pay close attention if you are exhausted, explained MacMillan.

So what can you do to improve your quality of sleep? Yom recommended practicing good sleep hygiene. That means getting between seven and nine hours of sleep each night, not using electronics for 30-60 minutes before going to sleep, using your bed only for sex and sleep, and avoiding alcohol and caffeine before bed. Additionally, she suggested taking a warm bath or shower at night, creating a dark and comfortable sleep environment, and eating a small protein snack before heading to bed.

MacMillan suggested wearing blue-light blocking glasses from dusk onwards or at least an hour before bed, which can help treat and prevent mania in people with bipolar disorders. “I tell all my patients to use filters on their electronic devices, such as Night Shift on iPhones, to remove blue light when using devices after dark. Blue wavelengths of light tell the brain it is time to wake up.” Sleeping with your phone in another room, turning off notifications at night, and only allowing emergency calls to come through can also be useful for individuals who are easily disturbed overnight.

Lewin believes that staying active and doing exercise consistently helps regulate our sleeping patterns, too. In addition to shutting off stimulation from screens, such as TV or phones, she recommended using meditation or relaxation exercises before bed. Moreover, creating a bedtime routine, for example showering and then drinking herbal tea and reading, can send a signal to the brain that it’s time to sleep. “If a person is struggling with insomnia, cognitive behavioral therapy has been proven to be highly effective,” she said.