Sleep 101: Why Sleep Is So Important to Your Health

Erica Jansen

Research Assistant Professor of Nutritional Sciences

March 2, 2020

What is sleep exactly, and how does it help us stay healthy?

Sleep is an altered state of consciousness where we have limited interactions with our surroundings and are relatively quiet and still (depending on the stage of sleep). Contrary to our quiet physical state, the brain is very active during sleep, carrying out many important functions. Sleep is essential to every process in the body, affecting our physical and mental functioning the next day, our ability to fight disease and develop immunity, and our metabolism and chronic disease risk. Sleep is truly interdisciplinary because it touches every aspect of health.

How does what we eat impact our sleep?

It is well-known that certain substances, such as caffeine, can affect the onset of sleep in a negative way. On the other hand, evidence is growing that shows how other foods like tart cherries, kiwi, fatty fish (like salmon and tuna), and malted milk may have beneficial effects on sleep. More recently, studies have shown that healthy dietary patterns overall—not just specific foods—could be associated with longer sleep duration and shorter time to fall asleep.

Why is sleep so important for young children, and what are some of the common negative effects of poor sleep?

Sleep is important for every part of the body, and it is especially important for young children as their bodies and minds develop. In young children, lack of sleep or poor quality sleep can be associated with difficult behaviors, lower capacity to learn and retain information, and a propensity for poor eating patterns and weight gain.

What sleep needs do adolescents have, and what does this mean for the current conversations we're having around school-day start times?

Adolescents need around 8-10 hours of sleep per night, but a high proportion do not get that amount. For example, recent estimates suggest that 60 percent of middle schoolers and 70 percent of high schoolers don’t get adequate sleep on school nights. This figure is even higher for Michigan high schoolers, which is at 80 percent. One of the main reasons adolescents are so sleep-deprived is that biological changes in their brain affect when they feel sleepy. So even if they are sleep-deprived, they often can’t go to bed early because their brain is not yet prepared to sleep.

The problem with these delayed bedtimes is that school or before-school activities often start very early, so adolescents may end up chronically sleep deprived. In school districts that have enacted later school start times, research is consistently showing that students get more sleep and as a result have fewer motor vehicle accidents, better grades, and improved mental health.

Every spring and fall we change our clocks by an hour. What health impacts does this change have on individuals and on the public’s health?

There are many calls from the sleep-research community to eliminate daylight savings time. When our clocks are pushed forward, people lose one hour of sleep. This one-hour sleep loss is associated with significantly more motor vehicle accidents as well as cardiac events. When our clocks move backward, we might think that extra hour helps us. But our sleep patterns are disrupted by any change like this, so the fall time change may also lead to negative health impacts. In general, these universal time changes create a significant and negative burden on the public’s health.

How important is sleep for our mental health?

Sleep and mental health go hand-in-hand. Good sleep is essential for maintaining our baseline mental health, as one night of sleep deprivation can dramatically affect mood the next day. Chronic exposure to poor sleep quality is associated with depression, anxiety, and other conditions. There are also bidirectional associations—meaning that experiencing anxiety and depression very often affects sleep, which then impacts our ability to cope with the anxiety and depression, and so on.

How does alcohol impact sleep?

Although alcohol may help a person fall asleep quickly, it hinders sleep quality, often causing fragmented (interrupted) sleep. When consuming alcohol, it is recommended to do so several hours before bedtime so that the alcohol is completely out of the system before sleep.

Does screen time really affect our sleep?

There is evidence to show that screen use right before bed could impact sleep. One reason is that the blue light emitted from these devices can affect the secretion of melatonin, the hormone that helps signal to the body that it is time to fall asleep. Other reasons include the content of what is on the screen. If you watch a scary movie, read an emotionally-driven article, or consume any other anxiety-producing content on your screen, it can affect your ability to fall asleep. Sleep clinicians recommend putting away all screens at least one hour before bed and to instead do some light reading or other relaxing activity.

About the Author

Dr. Erica Jansen is a nutritional epidemiologist who focuses on diet and sleep in relation to pediatric health. Her research covers how early nutritional environments affect childhood obesity and the timing of puberty, how various aspects of sleep—duration, timing, and quality—affect development of cardiometabolic risk, the bidirectional associations between sleep and diet, and epigenetic markers that underlie relationships between sleep and cardiometabolic health.

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