You probably know firsthand that sleep affects mood. After a sleepless night, you may be more irritable, short-tempered, and vulnerable to stress. Once you sleep well, your mood often returns to normal.

Studies have shown that even partial sleep deprivation has a significant effect on mood. University of Pennsylvania researchers found that subjects who were limited to only 4.5 hours of sleep a night for one week reported feeling more stressed, angry, sad, and mentally exhausted. When the subjects resumed normal sleep, they reported a dramatic improvement in mood.

Not only does sleep affect mood, but mood and mental states can also affect sleep. Anxiety increases agitation and arousal, which make it hard to sleep. Stress also affects sleep by making the body aroused, awake, and alert. People who are under constant stress or who have abnormally exaggerated responses to stress tend to have sleep problems.

Insomnia and Psychological Problems

“There’s a big relationship between psychiatric and psychological problems and sleep. So people who are depressed or have anxiety often have trouble with sleep as part of those disorders,” says Dr. Lawrence Epstein, Medical Director of Sleep Health Centers and an instructor at Harvard Medical School.

Difficulty sleeping is sometimes the first symptom of depression. Studies have found that 15 to 20 percent of people diagnosed with insomnia will develop major depression.2 While sleep research is still exploring the relationship between depression and sleep, studies have shown that depressed people may have abnormal sleep patterns.

Sleep problems may, in turn, contribute to psychological problems. For example, chronic insomnia may increase an individual’s risk of developing a mood disorder, such as depression or anxiety. In one major study of 10,000 adults, people with insomnia were five times more likely to develop depression.4 Lack of sleep can be an even greater risk factor for anxiety. In the same study, people with insomnia were 20 times more likely to develop panic disorder (a type of anxiety disorder).5 Another study showed that insomnia is a reliable predictor of depression and many other psychiatric disorders, including all types of anxiety disorders.6

Addressing Sleep Problems Makes a Difference

If you sleep poorly and feel depressed, anxious, or less emotionally responsive, there are many treatments that can help. First, look at your sleep habits and see if there are steps that you can take on your own to improve the quantity and quality of your sleep. See Adopt Good Sleep Habits for tips on how to improve your sleep. If problems persist, you may wish to see a medical provider and ask about an evaluation for sleep problems and mental health concerns. After an evaluation and diagnosis, your provider can advise you on the best course of treatment. Options may include behavioral or other forms of therapy and/or medications. You can read about and watch a video of a behavioral sleep consultation in the Healthy Sleep module.

Even if you do not have underlying sleep problems, taking steps to ensure adequate sleep will lead to improved mood and well-being. Sheila, a Boston district attorney and mother, became sleep deprived due to the conflicting demands of a full-time job and caring for her young children. She began to feel cranky, irritable, and uncharacteristically depressed. When she got both of her children on a consistent sleep schedule, she herself started sleeping an average of seven to eight hours a night and her mood improved considerably.