Why Do We Need Sleep? We Feel Happier!

Why do we need sleep? Not getting enough sleep can have some unsettling consequences. Here’s how to get more sleep and start feeling better.

Are you crabby and short-tempered in the mornings? Why do we need sleep, anyway? Researchers at Tel Aviv University (TAU) found that skimping on slumber has a direct impact on part of the brain that affects your emotions — and that means too little sleep could trigger an increase in anxiety, make it harder to concentrate, and put you in a grumpy mood, too.

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Why do we need sleep? What happens when you don't get enough 

Millions of Americans don’t get enough sleep, and the Centers for Disease Control and Prevention (CDC) calls too little sleep a major public health problem. But here’s the good news: If you are sleeping six hours or fewer, there may be a quick fix for feeling grouchy and unfocused. Simply getting more sleep for even one night can change how your brain responds to information and result in a more focused and less cranky outlook, according to the TAU study. 

The researchers put 18 volunteers through tests performed after the research subjects were kept awake all night and repeated after the study participants had a good night’s sleep. The volunteers were shown images tied to emotional responses most people consider positive (a pet cat), negative (a mutilated body), and neutral (a spoon) and were asked to press a button at certain moments. The research team noted which images distracted the volunteers from accurately and quickly performing the designated task.

In order to document whether brain activity was altered during the tests when the participants were sleep deprived, the study participants were monitored with functional magnetic resonance imaging, which detects changes in blood oxygenation and flow in specific areas of the brain, and electroencephalography, which records the brain’s electrical activity. 

The results showed that when the study participants were well rested, they were distracted during the tests only by emotional images. But when they were sleep-deprived, every image — whether positive, negative, or neutral — distracted them.

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What are the effects on the brain and body from lack of sleep?

The monitoring of brain activity revealed a likely explanation. The lack of sleep had a significant effect on the amygdala, part of the brain responsible for how emotions are processed. 

"These results reveal that, without sleep, the mere recognition of what is an emotional and what is a neutral event is disrupted," said TAU neuroscientist Talma Hendler, MD, PhD, who headed the research. “We may experience similar emotional provocations from all incoming events, even neutral ones, and lose our ability to sort out more or less important information. This can lead to biased cognitive processing and poor judgment as well as anxiety.”

The findings offer evidence that simply getting enough sleep plays an important role in promoting emotional and mental health. And they may explain why you over-react to things — big and small — at home and work if you didn’t get enough sleep the night before. “The ability of the brain to tell what's important is compromised. It's as if suddenly everything is important," Hendler said.

Interest in the importance of sleep has grown as scientists have found links between a lack of sufficient sleep and a host of chronic diseases, including diabetes, heart disease, and depression, according to the CDC. 

The amount of sleep you need every day tends to change over the course of your life. The National Heart Lung and Blood Institute (NHLBI) website provides a chart of average adequate hours of sleep for various age groups.

If you're worried about whether you're getting enough sleep, keep a sleep diary for several weeks. Record how many hours you sleep each night, how rested and alert you feel when you wake up in the morning, and whether you feel sleepy during the day. The NHLBI advises sharing the results of your diary with your doctor and talking about how you can improve your sleep. Sleep problems may be a symptom of a sleep disorder or other medial condition.

You can download the NHLBI’s free “Your Guide to Healthy Sleep”  for a sample sleep diary and information on what causes sleep problems and tips for getting more sleep.

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