How Screen Time Affects Your Toddler or Preschooler's Sleep

Updated: Sep 8


Undoubtedly, you have heard that screen time too close to your child's bedtime is bad for sleep. But to what extent is this true? Is screen time bad only if your child is watching a show as they fall asleep? What if they just like to watch a lot of TV during the day, but don't watch it in the evening? Or, how about if watching a YouTube video on the iPad is the one thing that relaxes your child and seems to actually help him fall asleep? Instead of speculating, or calling all screen time bad, let's dive into what research teaches us about how screen time affects children's sleep.

Check out these 4 ways screen time can affect your child's sleep, according to science.

1. Light exposure before sleep alters sleep wake cycles

Many studies have shown that exposure to a bright light on a screen alters sleep-wake cycles and biological rhythms in people. Although most of these studies have been conducted in adults, it is thought that the same effects apply to children. Let's dive into the details.

Melatonin

It is not a new finding that nighttime melatonin can be suppressed by exposure to bright light. The first study showing this was conducted in 1980 and demonstrated that exposure to very bright light (about 2x the brightness of a typical office lighting) suppressed nighttime melatonin secretion. Many more recent studies, however, have shown these same effects at much lower light intensities (more like lighting in a typical well lit home).

A study (1) in 2003 by Higuchi et al., however, demonstrated suppressed nighttime melatonin at an even lower level of light intensity. During this study, the lighting of the room was very dim, but the display screen was bright. At this level of lighting, melatonin was found to be lower only when the activity on the screen was exciting (playing a game) as compared to boring (completing simple math problems). Melatonin levels were not affected if the activity on the screen was boring, even if the screen was bright. Nor were they affected if the screen was dim.

Researchers believe that because those performing the exciting activity maintained their gaze at the screen as compared to those performing a boring activity, the prolonged gaze impacted the decrease in melatonin. Additionally, the more exciting activity seemed to activate the subject's sympathetic nervous system, causing their pupils to be wider, thus letting in more light. The more light that is let in, the greater the effect on melatonin.

Without replicating this study on children viewing a show or playing a game, we don't know to what extent their typical activities on the screen would affect their melatonin levels. However, after seeing how my kids glue their eyes to the screens they are watching, I would suspect that a child watching a show would be closer to an exciting activity than a boring activity.

Circadian Rhythm

During the same 2003 study mentioned above, where the subjects were exposed to a bright or dim screen in a dimly lit room, participating in either exciting and boring activities, body temperature was measured as a marker of circadian rhythm. It was found that body temperature was higher, thus delaying circadian rhythm, in those viewing a bright screen performing an exciting activity. Researchers believe that body temperature is regulated by melatonin. Therefore, the delayed secretion of melatonin has been shown to actually delay the onset of the circadian rhythm.

Sleepiness

Finally, in the same 2003 study mentioned above, sleepiness was not affected, despite melatonin levels being lower and circadian rhythm being altered. Thus, one may feel sleepy but be unable to fall asleep if the processes in their body are not lined up for sleep.

What Does This Mean?

With suppression of the nighttime melatonin, light exposure at night has the potential to substantially alter physiology and behavior. How?

  • Melatonin secretion can shorten, leading to less sleep.

  • Altered circadian rhythms impact hormone regulation including glucocorticoids. This can impact behavior, mental health, hormones, and the immune system. (4)

Recommendation

Avoid bright screens and exciting screen time activities in the evening

2. TV in the Evening Leads to More Sleep Disturbances

A study (3) by Garrison et al. in 2011 sought to find out if timing, content (see #4), co-use by an adult (see #4), or screen use in the bedroom (see #3) affected sleep in preschoolers. The researchers in this study found that preschool aged children who watched TV in the evening (after 7PM) reported more challenges related to sleep compared to those who did not watch TV after 7PM. They also found that for every additional hour of media use in the evening, sleep challenges worsened. Sleep challenges most commonly noted by parents included longer time to fall asleep (>20 minutes) and overnight waking.

Children who watched TV in the evenings (after 7PM) were also more likely to watch shows with ratings for older children or adults, although most of the content (80%) was the same as their daytime child-appropriate shows. Finally, this study found that while total daily screen time did negatively impact sleep, evening viewing had a greater impact than daytime viewing.

Additionally, a study (2) by Paavonen in 2006 found that children who watched TV in the evenings had a greater risk for Sleep-Wake Transition Disorder (see definition in #4).

Recommendation

Avoid media use for your toddler/preschooler after 7PM.

3. Preschoolers with TV in the Bedroom Take Longer to Fall Asleep (and have other sleep problems)

A study (3) by Garrison et al. in 2011 was completed to see what type of impact televisions in the bedroom have on sleep of preschool aged children. This study found that children who have a TV in their bedroom are more likely to report sleep problems 5-7 days per week and their parents were more likely to report daytime sleepiness. The most reported sleep problem was how long it took their child to fall asleep. Other reported problems included nightmares, daytime tiredness, and a hard time waking in the morning.

Additionally, the study found that children with a TV in their bedroom were more likely to watch an additional 40 minutes of TV throughout the day. Children with a TV in their bedroom also consumed significantly more violent or scary content, or content meant for older children or adults. See # 4 for more on how violent content impacts sleep in children.

Multiple other studies found similar findings for infants (6), preschool (7), and school aged children, ages 3-10 years old (5).

Studies between 2004-2009 found that 20-43% of preschool aged children have a TV in their bedroom. A more recent study (8), published in 2018, showed that 49.6% of children ages 2-5 use a screen within 1 hour of bedtime and 41% used screens in their bedroom.

What Does This Mean?

If your child takes a long time falling asleep, has nightmares, has a hard time waking in the morning, or seems tired during the day, remove the TV (or tablet) from their bedroom. Better yet, avoid screen in your child's bedroom.

4. Inappropriate content can cause nightmares, difficulty falling asleep, and more

Not all screen time is created equal when it comes to negatively impacting sleep. First, the good news. According to a study (2) by Paavonen et al. in 2006, children who actively watch a lot of children's television programs during the day were NO MORE LIKELY to have sleep challenges than children who watch just a small amount of children's television programs during the day. Yay! Daniel Tiger marathons may commence!

Now, the not so good news. Children aged 5-6, who actively OR passively watch programs with adult content including adult-targeted movies, shows, news, and police shows were more likely to have challenges related to sleep. These effects were seen not just when the child sat down to actively watch shows with adult content, but also when the shows were on in the background and the child was not actively paying attention. Yikes.

Check out how each category affected the children's sleep:


Movies with adult content

  • disorders of initiating and maintaining sleep*

  • sleep wake transition disorders*

  • night sweats

News

  • sleep transition disorder*

  • night sweats

Police Series

  • ​sleep wake transition disorders*

  • night sweats

  • disorders of excessive somnolence*

TV Programs with adult content

  • sleep wake transition disorders*

Sports

  • no sleep challenges associated

*see definitions below

Similarly, a study (3) by Garrison et al. concluded that preschoolers (ages 3-5) who watched shows with violence had an increased likelihood of experiencing nightmares, a hard time waking the in morning, and daytime tiredness. They also found that daytime consumption of age-appropriate and non-violent shows did not affect sleep. The negative effects of watching shows intended for older children or adults was NOT mitigated by co-watching with an adult. Nor did it vary according to the type of violence (fantasy, mild slapstick, sports, realistic) or whether it was animated or live action. This study found that ratings for movies (G, PG, etc) and TV shows (Y, Y7, etc) were an effective guide for choosing what type of shows your child watches.

Definitions:

*Disorders of Initiating and Maintaining Sleep - Includes sleep duration, sleep latency, going to bed reluctantly, difficulty falling asleep, falling asleep anxiety, night awakenings, difficulty in falling asleep after awakening

*Sleep Transition Disorder - Includes hypnic jerks, rhythmic movement disorders, hypnagogic hallucinations, nocturnal hyperkinesia, sleep talking, teeth grinding/jaw clenching

*Disorders of Excessive Somnolence - Includes difficulty in waking up, tired when waking up, sleep paralysis, daytime somnolence, sleep attacks, bed wetting

What Does This Mean?

Avoid exposing your child (actively or passively) to programs not intended for your child's developmental age group.

References

1 Higuchi, et al. Effects of VDT tasks with a bright display at night on melatonin, core temperature, heart rate, and sleepiness J Appl Physiol (2003) May;94(5):1773-6. doi: 10.1152/japplphysiol.00616.2002. Epub 2003 Jan 17.

2 Paavonen et al. TV exposure associated with sleep disturbances in 5- to 6-year-old children. . Sleep Res. (2006) 15, 154–161

3 Garrison et al. Media Use and Child Sleep: The Impact of Content, Timing, and Environment. PEDIATRICS Volume 128, Number 1, July 2011.

4 Walker II et al. Translational Psychiatry (2020) 10:28 https://doi.org/10.1038/s41398-020-0694-0

5 Owens, et al. Television-viewing Habits and Sleep Disturbance in School Children. Pediatrics September 1999, 104 (3) e27

6 . Vijakkhana N, et al. Evening media exposure reduces night‐time sleep. Acta Paediatr 2015;104(3):306–12.

7 1. Brockmann PE, et al. Impact of television on the quality of sleep in preschool children. Sleep Med 2015;20:140–4.

8 Emond, J., et al. Household chaos and screen media use among preschool-aged children: a cross-sectional study. BMC Public Health. 2018; 18: 1210.

Katie Ramirez, RN, BSN, CLC

Born Happy, Owner and Coach

Katie Ramirez is a Registered Nurse, Certified Lactation Counselor, and Coach for parents of babies and toddlers. She has spent more than a decade serving patients at major university hospitals such as Vanderbilt University and Penn State University Medical Centers. Katie now spends her time supporting and empowering parents of babies and toddlers as owner and coach for Born Happy.

Katie is the proud mother of two beautiful children, Roberto (age 7), and Veronica (age 5). She has a passion for health, wellness, and happy children, and believes that, with the necessary knowledge and support, all parents can live happy.

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