作者：Pam Harrison
出處：WebMD醫學新聞
January 1, 2010 — 根據1月1日Sleep期刊的研究，相較於父母親規定就寢時間在晚上10點或之前的青少年，父母親規定就寢時間在半夜12點鐘或之後者，有24%更可能有憂鬱、20%更可能出現自殺意念。
這些發現認為，父母親規定的就寢時間較早，有助於青少年有比較充足的睡眠而預防憂鬱。紐約市哥倫比亞大學醫學中心的James Gangwisch博士與多所中心的研究夥伴發現，「National Longitudinal Study of Adolescent Health (Add Health)」研究中的15,659名青少年的平均睡眠量報告為7小時53分鐘，比美國睡眠醫學會建議的青少年睡眠9小時以上少很多。
不過，父母親規定就寢時間在晚上10點或之前的青少年，平均睡眠時間比那些晚上11點就寢者多了33分鐘，比那些晚上12點之後睡眠者多了40分鐘。相較於每晚睡眠有8小時的青少年，每晚睡眠時間平均小於等於5小時的青少年，有71%更可能有憂鬱、48%更可能會有自殺想法。
Gangwisch博士向Medscape Neurology表示，短睡眠期可能是憂鬱的症狀或者是憂鬱的起因，所以我們試圖藉由父母親規定的就寢時間來瞭解此問題，因為如果讓小孩自己決定何時就寢，將會成為缺乏睡眠只是憂鬱症狀的論述，而我們的研究則是支持缺乏睡眠是憂鬱起因的觀念。
【Add Health研究】
Add Health研究於1994至1996年間包括了美國全國7-12年級青少年的代表樣本。使用18個問題版的「流行病學研究中心之憂鬱量表」，評估研究對象的憂鬱症狀，根據對「過去12個月間，你是否曾慎重考慮自殺？」這個問題的反應確定有無自殺意念。
如同研究者指出的，超過三分之二的Add Health研究對象報告指出，遵守他們的父母親所指定的就寢時間上床睡覺。在未校正分析中，相較於規定就寢時間在晚上10點者，父母親規定就寢時間在半夜12點鐘或之後的青少年，有42%比較可能會憂鬱，規定就寢時間在晚上11點有15%比較可能會憂鬱。
同樣在未校正分析中，相較於規定就寢時間在晚上10點者，父母親規定就寢時間在半夜12點鐘或之後、規定就寢時間在晚上11點的青少年，分別有30%和15%比較可能有自殺意念。根據使用的模式不同，風險值變小。
【父母親規定之就寢時間、共變項、憂鬱與自殺意念之間的關係】
| 有憂鬱 (n = 1050 人[7%]) | 無憂鬱 (n = 14,60 人 [93%]) | P 值 | 有自殺意念(n = 2038 人 [13%]) | 無自殺意念 (n = 13,621 人 [87%]) | P 值 |
青少年報告之平均就寢時間 | 平均是晚上 10:36
| 平均是晚上 10:25 | .0834 | 平均是晚上 10:34 | 平均是晚上 10:25 | .0227 |
青少年報告之平均睡眠期間 | 7 小時 23 分鐘 | 7 小時 55 分鐘 | .0001 | 7 小時 36 分鐘 | 7 小時 55 分鐘 | .0001 |
父母親規定的就寢時間 |
晚上 10 點或之前 | n = 495 人 (6%) | n = 7976 人 (94%) | .0001 | n = 1012 人 (12%) | n = 7459 人 (88%) | .0012 |
晚上 11 點 | n = 231 人 (7%) | n = 3108 人 (93%) |
| n = 451 人 (14%) | n = 2888 人 (86%) |
|
半夜 12 點或之後 | n = 324 人 (8%) | n = 3525 人 (92%) |
| n = 575 人 (15%) | n = 3274 人 (85%) |
|
Gangwisch博士指出，青少年現在因為有許多使其分心的娛樂而希望晚點就寢，加上得早起以免上學遲到，使他們很容易沒有足夠睡眠。我們總是說，有充足的睡眠對於心智健康相當重要，從事其他活動而減少睡眠量將會有負面影響，包括增加憂鬱風險。
【獲證明的經驗法則】
佛羅里達睡眠研究中心的William Kohler醫師向Medscape Neurology提出對此研究的評論，該研究證明了缺乏睡眠導致認知困難的經驗法則。
雖然這類問卷研究有固有的不精確性，但是它研究樣本夠多，是一個很好的研究。如他所指出的，報告中沒有青少年的睡眠品質資料，所以研究對象有可能躺在床上8小時但是實際睡眠時間少。
但是，Kohler醫師認為，該研究強調了醫師詢問青少年病患之睡眠習慣— 何時上床睡覺、他們有多少睡眠或認為自己有多少睡眠—的重要性，以確保不是因為不佳之睡眠習慣引起的憂鬱。
他也認為，學校必須注意學生開始上課的時間，因為不論投注多少經費在公共教育，如果小孩必須在早上5點起床上學，他們很可能因為睡眠被剝奪而無法適當學習。
哥倫比亞大學的Robert Wood Johnson Health and Society Scholars Program提供本研究之財務支持，不過本研究並非產業界支持的研究。Gangwisch博士以及Kohler醫師皆宣告沒有相關財務關係。
Depression, Suicidal Ideation More Likely in Adolescents With Late vs Earlier Set Bedtimes
By Pam Harrison
Medscape Medical News
January 1, 2010 — Adolescents whose parents mandate bedtimes of midnight or later are 24% more likely to be depressed and 20% more likely to express suicidal ideation than adolescents whose parents set bedtimes of 10 pm or earlier, according to a study in the January 1 issue of Sleep.
These findings suggest that earlier parentally set bedtimes may help protect adolescents from depression by ensuring they get enough sleep. James Gangwisch, PhD, Columbia University Medical Center, New York City, and multicenter colleagues found that the average amount of sleep reported by 15,659 adolescents involved in the National Longitudinal Study of Adolescent Health (Add Health) was 7 hours and 53 minutes — considerably less than the 9 or more hours recommended for adolescents by the American Academy of Sleep Medicine.
However, adolescents whose parents had set a bedtime of 10 pm or earlier slept 33 minutes more, on average, than those with a bedtime of 11 pm, and 40 minutes more on average than adolescents with a parental bedtime of midnight or later. Adolescents who reported getting on average 5 or fewer hours of sleep per night were also 71% more likely to be depressed and 48% more likely to think about committing suicide than adolescents who reported getting 8 hours of sleep a night.
"Short sleep duration could be either a symptom of depression or it could be causative of depression, so we tried to get at this question by looking at parentally mandated bedtimes because if you leave it up to a child as to when they go to bed, an argument could be made that [lack of] sleep is simply a symptom of depression," Dr. Gangwisch told Medscape Neurology. "And our study lends support to the idea that lack of sleep could be causative for depression."
Add Health
Add Health involved a nationally representative sample of adolescents in the United States who were in grades 7 to 12 between 1994 and 1996. An 18-item version of the Centers for Epidemiologic Study–Depression Scale was administered to assess individuals for the presence of depressive symptoms, and the presence of suicidal ideation was determined by responses to the question: "During the past 12 months, did you ever seriously think about committing suicide?"
As investigators note, more than two thirds of Add Health participants reported going to bed at a time that complied with their parents' reported set bedtime. In unadjusted analyses, adolescents with late parentally mandated bedtimes of midnight and later were 42% more likely to be depressed, and those with set bedtimes of 11 pm were 15% more like to be depressed, than adolescents with set bedtimes of 10 pm.
Again in unadjusted analyses, adolescents with parentally set bedtimes of midnight or later and 11 pm were 30% and 15% more likely to suffer from suicidal ideation, respectively, in comparison with adolescents with parental set bedtimes of 10 pm. Risks were attenuated depending on the model used.
Relationships Among Parental Set Bedtimes, Covariates, Depression, and Suicidal Ideation
| ? | Depression Yes (n = 1050 [7%]) | Depression No (n = 14,609 [93%]) | P Value | Suicidal ideation Yes (n = 2038 [13%]) | Suicidal ideation No (n = 13,621 [87%]) | P Value |
| Adolescent-reported average bedtime | Mean 10:36 pm | Mean 10:25 pm | .0834 | Mean 10:34 pm | Mean 10:25 PM | .0227 |
| Adolescent-reported average sleep duration | 7 h 23 min | 7 h 55 min | .0001 | 7 h 36 min | 7 h 55 min | .0001 |
| Parental set bedtime |
| 10 pm or earlier | n = 495 (6%) | n = 7976 (94%) | .0001 | n = 1012 (12%) | n = 7459 (88%) | .0012 |
| By 11 pm | n = 231 (7%) | n = 3108 (93%) | ? | n = 451 (14%) | n = 2888 (86%) | ? |
| By or after midnight | n = 324 (8%) | n = 3525 (92%) | ? | n = 575 (15%) | n = 3274 (85%) | ? |
"Adolescents want to go to bed later now because there are so many different distractions, plus they have to get up really early for school, so it's easy for them not to get enough sleep," Dr. Gangwisch noted. "But what we are saying is that getting adequate sleep is very important for mental health, and compromising on the amount of sleep by doing other activities can have negative consequences, including a increased risk of depression."
Substantiated Empirical Belief
Commenting on the study, William Kohler, MD, from the Florida Sleep Institute, Springhill, told
Medscape Neurology that the study "substantiated the empirical belief that lack of sleep leads to difficulties with cognition." Even though inherent inaccuracies do occur with a questionnaire-based study such as this one, "the sample size was large, and it was a very good study." There was, as he indicated, no information on the quality of sleep reported by the adolescents, so that participants might have been in bed 8 hours but had gotten little sleep.
Still, Dr. Kohler feels that the study underscored how important it is for physicians to ask adolescent patients about their sleep habits — what time they go to bed, how much sleep they have or perceive they get — to make sure poor sleeping habits are not contributing to underlying depression.
He also feels that schools need to look at start times for students because "no matter how much money we throw at public education, if children are getting up at 5 in the morning to get to school, they are not going to learn properly because they are sleep-deprived."
Financial support for this study was provided by a grant from the Robert Wood Johnson Health and Society Scholars Program at Columbia University, but it was not an industry-supported study. Dr. Gangwisch and Dr. Kohler have disclosed no relevant financial relationships.
Sleep. 2010;33(1):97-106.
