German World of Warcraft players’ sleeping patterns in relation to depressive symptoms (Lemola et al., 2011)

Ika Musume playing past bedtime (Shinryaku! Ika Musume)

They say professors don’t sleep at all because the night is the only time when they could their research papers done. In my case, this would be from those pesky things that I call other people.  But, I don’t habitually work those hours as the aftermath are often costly.

Sakari Lemola (University of Basel) and his European colleagues have published a sleep-related videogame study in Personality and Individual Differences on German World of Warcraft players. The study seemed pretty obvious that a good night’s sleep is one of the habits towards a healthy life and that playing videogames past your bedtime would pose a problem.


This study investigated whether the amount and circadian time of habitual computer game playing were related to depressive symptoms in adolescents and young adults. We expected that habitual late playing relates to more depressive symptoms beyond the effect of the total time of computer game playing as playing at night may involve short, irregular, and disturbed sleep as well as misalignment of the circadian rhythm. 646 adolescents and young adults (ages 13–30; 90.9% males) who play the internet role-playing game World of Warcraft completed an online questionnaire. Habitual computer game playing between 10 pm and 6 am was related to an increased risk of high depression scores independent of the total amount of playing. Adolescents (ages 13–17 years) were most vulnerable when habitually playing during early night (i.e., 10–12 pm), while emergent adults (ages 18–22 years) showed more vulnerability when habitually playing late at night (i.e., after 2 am). The effect was partly mediated by daytime sleepiness but not by sleep loss or insomnia problems.

I’m usually the first one in and the last one out of the building; between that are periods of head bobbing.

Head Bobbing Run (A Channel)

The authors are interested when WoW players play rather than the total amount of time spent on the videogame. As some studies have found, total amount of play time is not an accurate way to measure well-being or addiction. If you think more of the nuances, an individual playing mostly during the day and has a regular bedtime would seem logically to better off psychological than someone who plays well into the night with only a few hours of sleep before going to class. As some undergrads who do this kind of thing by handing in their nonsensical papers late.


Participants: An anonymous online survey was posted to WoW related forums during winter 2009-2010. They got 646 participants, 90.9% are men, the average age is 19.7 (SD = 3.6) with a range between 13 to 30 years old. The authors categorized the sample into three age groups: Adolescents (13-17 year olds, n = 190), emerging adults (18-22 year olds, n = 347), young adults (23-30 year olds, n =129). They excluded about 50 participants who were outside of the age range.  Most of the participants live in Germany (n = 548), followed by Austria and Switzerland.


Demographics and Computer playing: demographics, obviously. The participants were asked the total number of hours played in WoW in a typical week. They were asked how often they played WoW in certain time periods in a given week (e.g. 6-12 am, 12am-6pm, etc.) on a 4-point scale (less than once a week, 1-2 days per week, 3-4 to 5-7 days per week).

Sleep questionnaire: A mixture of various sleep questionnaires that measured for sleep duration, sleep problems and daytime sleepiness: Insomnia Severity Index, Epworth Sleepiness Scale, and an unnamed third questionnaire that seem to come from a manual.

Depressive symptoms: The short version of the ‘Allgemine Depressionsskala’ (ADS-K), the German-language version of the original English ‘Center for Epidemiological Studies Depression Scale’ (CES-D). A commonly used scale for depression.


The average playtime for each age group is 24.1 hr/week, 22.4 hr/week, and 19.4 hr/week, respectively. The play time seemed similar to other studies (Williams et al., 2008; Gentile et al., 2011). 7 participants have reported in playing more than 80 hours per week! The most common time periods that are played on a near daily basis (5-7days/week) for this sample of WoW players are between 6pm-8pm, 8pm-10pm and trailing off for 10pm-12pm of which my estimated average 25% are playing during that time period. A greater percentage among emerging adults played with some regularity well beyond midnight (and dammit I’m not sure if I’m reading that table right). Beyond 2am, a very small number of players are habitually playing in those ungodly hours.

The age group differ between each other in terms of sleep time during weekends, the young adults sleep less during weekend (8.7 hrs), and are less depressed (M= 8.5 versus the other M = 10.6). Anyways, the average depression scores are pretty much similar in relation to a general population sample, said the authors.

They conducted logistic regressions which would take account all of the measures they used in the survey. Their analyses with the whole sample is that there are increased risk for depressive symptoms for habitual night playing whereas daytime play (which is pretty rare among all age groups) is not related to depression risks. Just out of curiosity, I’m just wondering whether players who play irregular hours, like early morning and 2am shifts combined, are more likely at risk for depressive symptoms. Breaking down the analysis into separate age groups, the increased risk for depressive symptoms are associated to 10-12pm for adolescents and 2am-6am for emerging adults. There were no significant increased risks among young adults.

In terms of total hours of playtime per week, they split the sample into two groups by the median: 19hr/week vs. 20+hr/week groups. Their analysis found no statistical significance in the number of hours per week. Well, if you have the article, the error bars for 20hr+ group are huge! If they split the sample in three or four ways, I am pretty confident that those who play more than 30hrs will have significantly higher depressive symptom scores than the rest. It would hopefully reveal a significant interaction effects with the time periods of which their current analysis revealed none. In any case, the message indicates that play time after 10 pm would entail increasing risk for depressive symptoms. So on a regular basis, the later your play time into the night, the higher the risk.

The authors conducted a structural equation modeling to test the pathways between playtime in WoW, the sleeping variables and the depressive symptoms. So their structural model revealed that playing after 10pm (the 10pm-12pm and 12pm-2am periods, specifically) cuts down their amount of sleep during weekdays and weekends, the latter did not significantly affect their depressive symptoms. The pathway for daytime sleepiness is rather tenuous as late-night young adults are sleepier during the day, but this had no relation to depressive symptoms whereas this becomes relevant for emerging adults. Participants’ habitual night-time playing, age, and sleeping problems have a significant relationships with depressive symptoms. Unfortunately, night-time play did not have a significant relationship with sleep problems, which seemed to indicate a complex picture. The author surmised that WoW may be less arousing than other videogames, or perhaps IMHO are just grinding away, so it’s akin to watching late night television. But, I don’t know what goes on during those late night periods.

The authors used habitual night time as a unique variable between the mediators/moderators of the sleep variables with depressive symptoms as the outcome/dependent variable. What they constructed is a very narrow model, so there are a lot of things missing in the model, such as videogame motivations, passion, social competence, coping skills, interpersonal relationship quality, need satisfaction, size of their social network are some variables at the top of my head.

The authors cautioned that the relationships are only correlational, so there’s the possibility that depressive symptoms may lead to late night play times. They used self-reported online questionnaires which doesn’t seem like a problem to me, but argued that having objective measures, like EEG would be better. The study surveyed mostly male German-speaking WoW players, so it doesn’t apply very well to other videogame genres, like players in Team Fortress 2.

To sum the study, go to bed on time. Plan your game ahead of time so that you would complete your quest or errands when it’s bedtime.

Lemola, S., Brand, S., Vogler, N., Perkinson-Gloor, N., Allemand, M., & Grob, A. (2011). Habitual computer game playing at night is related to depressive symptoms. Personality and Individual Differences , 51 (2), 117-122. DOI: 10.1016/j.paid.2011.03.024

One thought on “German World of Warcraft players’ sleeping patterns in relation to depressive symptoms (Lemola et al., 2011)

  1. I am both a graduate student as well as a World of Warcraft player, so I find this study very interesting. I too have found that staying up late to play games does affect my ability to work efficiently the next day. I would rather devote those late-night hours to my graduate research anyway, since I find I am most productive once the sun goes down.

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