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By Dennis Miller, BHC Senior Writer

Most parents of young children are keenly aware that their kids need significantly more sleep than adults, and set bedtimes to ensure that they get it. But a new study provides an important reminder that adolescents, too, need significantly more sleep than adults, and warns that the consequences of not getting it can include mental health disorders.

The study, recently published in the journal Sleep, found that adolescents whose parents do not set an early enough bedtime face a significantly higher risk of depression or suicidal thoughts. “Adolescents with parental-set bedtimes of midnight or later were 24-percent more likely to suffer from depression and 20-percent more likely to have suicidal thoughts than adolescents with parental-set bedtimes of 10 p.m. or earlier,” says the study’s lead researcher, James Gangwisch, Ph.D., an Assistant Professor at Columbia University Medical Center in New York.

More alarmingly, the study found that the risk increases dramatically for every additional hour of sleep a teen misses. “Subjects who got five or less hours of sleep per night were 71 percent more likely to suffer from depression and 48 percent more likely to have suicidal thoughts,” Dr. Gangwisch explained.

Teens need extra sleep too

Many parents seem unaware of the fact that adolescents need just as much sleep as preadolescents do, and only an hour less than preschoolers. “Young children need ten hours of sleep per night, preadolescents about nine hours, and adolescents, research shows, also need about nine hours of sleep per night,” says Dr. Gangwisch. “And for adults, the recommendation is somewhere between seven and nine, depending upon the individual.”

The exact mechanics of how a lack of sleep may cause a higher risk of depression or suicidal thoughts remain somewhat of a mystery, although Dr. Gangwisch speculates it may simply be that growing teens, like younger children, are still growing and need to devote significant physical and mental resources to that process. “They’re growing and developing, their brains are developing still, and they need that extra rest to accomplish those things,” says Dr. Gangwisch.

Lack of sleep can also cause effects that closely mimic some symptoms of depression, which may be enough to actually cause it. “When we don’t get enough sleep it can make us feel tired and lethargic, experience lack of motivation and so forth ― irritability, too ― and those are symptoms of depression. So it can be seen through that that it could lead to depression,” he explains, “Also, some previous studies, such as experimental studies where they deprived a group of normal, healthy adults of sleep, have found that it leads to dysphoric mood.”

A chicken-and-egg question

That points to a chicken-and-the-egg relationship that still needs to be teased out about the links between sleep and depression. Sleepiness, lethargy and a lack of energy can be symptoms of depression, but does the depression cause them or are they the signs of not getting enough sleep, which may actually be root cause of the depression?

This study doesn’t answer that question definitively, but does give researchers more clues about the relationship. Dr. Gangwisch suspects the answer probably lies somewhere in between the two. “In epidemiological studies, short sleep duration has been shown to precede depression in studies with adults,” Dr. Gangwisch explains. “Again, it could be explained as a symptom of depression, but I think there’s definitely a bi-directional relationship there between short sleep duration and depression, whereby depression can cause short sleep duration but short sleep duration could cause or exasperate depressed mood. So even in someone who’s already suffering from depression and they have the symptom of short sleep duration, the idea is that perhaps treating the insomnia could also treat the depressed mood.”

The one thing that is certain is that most teens today, as most adults, are not getting sufficient sleep. A big factor in that are today’s more demanding time requirements, whether related to work, school or leisure, and the tendency of too many to try to make that time available by cutting back on sleep. ““There’s a lot of data to show that as a society, really we’re not getting enough sleep,” says Dr. Gangwisch. “I think we all hope to lead as full lives as possible and we try and pack our days with as many activities as possible. And oftentimes we put a lower priority on sleep at night in the hope that we’ll have more time available to do the things we want to do during the day. But if we do that, then it can compromise our mood and our motivation and our energy level and can make it harder for us to accomplish the things we want to accomplish during the day.”

Clinicians need to assess for sleep

Dr. Gangwisch hopes that the study’s results also prompt more behavioral health clinicians to consider sleep as a factor when evaluating patients who are experiencing symptoms of depression, suicidal thoughts or any other mental health disturbance. “As behavioral medicine practitioners, I think it’s important to keep sleep hygiene techniques in mind and pass those along to our patients whenever it’s called for,” he recommends. “And sleep hygiene techniques are basic commonsensical things that we’re all supposed to do but we often don’t do, such as trying to maintain a regular sleep schedule; trying to go to bed at the same time every night and get up at the same time every morning; having a comfortable sleep environment in terms of temperature, humidity and bedding; having a dark sleep environment; avoiding caffeine, nicotine and alcohol close before bedtime; trying to exercise during the day, but not too close to bedtime because that can get you revved up and make it harder for you to sleep.

To listen to BHC’s interview with Dr. Gangwisch, click on the media player above. The following is an edited transcript.

BHC: Tell us a bit more about the study and what you found.

JG: What we looked at were parental-set bedtimes and depression. And in a number of previous studies, lack of sleep or short sleep duration had been shown to precede depression, but that can be explained by short sleep duration or sleep difficulties being a symptom of depression.

So we tried to get at the bi-directional relationship between sleep and depression by conducting a quasi-experiment. The quasi-experiment is looking at parental-set bedtimes. We ended up with one group of kids, who have earlier parental-set bedtimes, where on average the kids end up going to bed earlier and they get more sleep. Then, in another group, we have kids who have later set bedtimes, and on average they go to bed later and get less sleep. So the kids with the earlier set bedtimes, we found, were less likely to suffer from depression and less likely to have suicidal thoughts.

An adolescent’s bedtime can be their personal choice of what time they want to go to bed, and it can be affected whether or not they suffer from depression. But whether the adolescent suffers from depression shouldn’t affect what time the parent sets for them to go to bed. So our study was a way to see whether short sleep can be causative of depression.

BHC: What age range are we referring to here?

JG: The adolescents in our study were in grades seven through twelve.

BHC: I understand there were some dramatic increases in the risk of being depressed for those who got less sleep. Can you talk about the numbers a little bit?

JG: Adolescents with parental set bedtimes of midnight or later were 24 percent more likely to suffer from depression and 20 percent more likely to have suicidal thoughts than adolescents with parental-set bedtimes of 10 p.m. or earlier. That was after controlling for a number of different covariates statistically.

Now, in terms of short sleep duration, subjects who got five or less hours of sleep per night were 71 percent more likely to suffer from depression and 48 percent more likely to have suicidal thoughts.

BHC: That’s a tremendous difference. How much sleep should teens get and how much did you find on average that they’re getting?

JG: Research studies have shown that adolescents need about nine hours of sleep per night. And in our study, the adolescents got on average just under eight hours on average. So they’re a little short of the recommended level. The data for our study was drawn from 1994 to 1996, so there are more distractions nowadays that can keep adolescents up, so we would imagine that those sleep durations are probably on average shorter now.

BHC: Just out of curiosity, when you say it was from 1994 to 1996, what data source were you mining to give you an indication of how parents were setting their bedtimes?

JG: It was data from Add Health ― the National Longitudinal Study of Adolescent Health. And that’s a school-based, nationally representative, probability-based sample of adolescents in the United States.

BHC: So that told you what the parents of kids were setting as the bedtimes. And then you were able to follow those individuals and determine an incidence of depression or thoughts of suicide, correct?

JG: Yes, it was actually a cross-sectional study. They did interviews with the parents and also with the adolescents. They asked the parents what time they set for their adolescents to go to bed and then they ask the adolescents what time they actually did go to bed. And then there is a screening tool for depression that’s administered at the same time.

Now the-parental set bedtime, we would presume that that is a pretty stable limit as to what time the adolescent can go to bed, and with school start times, that would put kind an earlier limit or morning time limit on what time the adolescent can sleep. So the presumption is the later the set bedtime, the later the adolescent will go to bed on average and the less sleep they’ll get.

BHC: Do you think there’s a misguided societal attitude out there that it’s really only young children whose sleep we need to worry about?

JG: Yes, most definitely. Young children need ten hours of sleep per night, preadolescents about nine hours, and adolescents, research shows. also need about nine hours of sleep per night. And then for adults, the recommendation is somewhere between seven and nine, depending upon the individual.

There’s a lot of data to show that as a society, really we’re not getting enough sleep.

BHC: Why is it do you think that teens and children need more sleep than adults do?

JG: I think that they’re growing and developing, their brains are developing still and they need that extra rest to accomplish those things.

BHC: Did the study suggest a possible mechanism, whether biochemical or bioelectrical or neurological, through which too little sleep is resulting in this increased risk of depression and suicide? And if not, can you maybe offer your own thoughts on why that’s so?

JG: We didn’t have any measures that would give us clues as to what exactly the mechanisms are. We did hypothesize some things based upon previous studies that had been done. For one thing, when we don’t get enough sleep it can make us feel tired and lethargic, experience lack of motivation and so forth ― irritability, too ― and those are symptoms of depression. So it can be seen through that that it could lead to depression.

Also, some previous studies, such as experimental studies where they deprived a group of normal, healthy adults of sleep, have found that it leads to dysphoric mood. And on another study with adolescents the same was found ― it compromised their mood. But those are studies with small sample sizes and limited generalizability. We drew data from a nationally represented sample, so it’s more generalizable.

BHC: What do you think the findings suggest for the workload that we put on teens in terms of homework, extra-curricular activities, pressures to excel academically, the socializing and TV watching and video game playing that goes on at night, and so forth. Do you think we as a society need to look carefully at that and start to inform parents and adolescents about it a little better?

JG: I think we all hope to lead as full lives as possible and we try and pack our days with as many activities as possible. And oftentimes we put a lower priority on sleep at night in the hope that we’ll have more time available to do the things we want to do during the day. But if we do that, then it can compromise our mood and our motivation and our energy level and can make it harder for us to accomplish the things we want to accomplish during the day.

So putting a higher priority on sleep and getting enough sleep at night can help us accomplish the things we want to do during the day by giving us the energy and the motivation and the ability to concentrate and focus that we need.

BHC: It also sounds like, beyond that, when you say those who got five hours or less of sleep were 71 percent more likely to report being depressed and 48 percent more likely to think about suicide, this really is a pretty important health issue, isn’t it?

JG: I definitely think so.

BHC: Is there a likely connection that we can make here as well ― and I think you might have just alluded to it: does research like this show that adults as well need to make sure they’re getting enough sleep, and could that often be an overlooked factor in depression in adults?

JG: Definitely, I think so. Our study was just with adolescents, but I would presume that these results would also apply in an adult population as well. Again, we try to look at the question through a quasi-experiment, and as adults, we don’t have externally mandated bedtimes, so you couldn’t really do such an experiment on adults. But, yeah, I think we definitely need to get adequate sleep as well.

BHC: Do you know of any research along those lines, looking at that question of adults and how much sleep they’re getting and the incidence of depression?

JG: Yes, in epidemiological studies, short sleep duration has been shown to precede depression in studies with adults. Again, it could be explained as a symptom of depression, but I think there’s definitely a bi-directional relationship there between short sleep duration and depression, whereby depression can cause short sleep duration but short sleep duration could cause or exasperate depressed mood.

So even in someone who’s already suffering from depression and they have the symptom of short sleep duration, the idea is that perhaps treating the insomnia could also treat the depressed mood.

BHC: So there’s a bit of a chicken-and-the-egg question there, I gather.

JG: Right.

BHC: Well, Dr. Gangwisch, I really appreciate you speaking with us today about your research. Anything more here you haven’t touched on that you’d like to add in closing?

JG: As behavioral medicine practitioners, I think it’s important to keep sleep hygiene techniques in mind and pass those along to our patients whenever it’s called for. And sleep hygiene techniques are basic commonsensical things that we’re all supposed to do but we often don’t do, such as trying to maintain a regular sleep schedule; trying to go to bed at the same time every night and get up at the same time every morning; having a comfortable sleep environment in terms of temperature, humidity and bedding; having a dark sleep environment; avoiding caffeine, nicotine and alcohol close before bedtime; trying to exercise during the day, but not too close to bedtime because that can get you revved up and make it harder for you to sleep.

So I think it’s important for practitioners to pass those sleep hygiene techniques along to their clients when it’s necessary, when they’re having problems with their sleep.

BHC: It’s interesting. I really haven’t seen much in the treatment protocols that I’ve seen for behavioral health clinicians about discussing sleep with a patient who’s presenting with symptoms of depression. Are you aware of that being any part of standard treatment protocols today?

JG: I’m really not, and I think it should be, and I’m hoping that the results of our study will perhaps lend more credence to the idea that it’s necessary. To me it’s a commonsensical thing. I mean, these are things that we’re all supposed to do. And I think people who suffer from mental health problems need to be reminded of those things. And help to implement them ― it’s one thing to give a person the information, but it’s another thing to help them actually implement those changes in their lives, to reprioritize the things that they need to do to help them put a higher emphasis on getting enough sleep at night.

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