Sleep genetics
A remarkable study published in Science this week identifies a rare mutation in the gene DEC2 which influences the duration of sleep in humans. The authors started with a family where patterns of short sleep (about 6 hours of sleep a night on non-workdays, versus ~8 hours for other people in the family) seemed to follow a Mendelian inheritance pattern. In a candidate gene resequencing study, they identified a mutation in all of two people–a mother and daughter–with the short sleep pattern.
In what can only be described as a ballsy move, the authors then invested what must have been a considerable amount of time and money on following up this mutation. Which, I emphasize again, was found in only two individuals in a single family. In particular, they generated mice carrying both of the human versions of the gene, and were thus able to explicitly compare the two human alleles in an animal model. (This is in contrast to most mouse studies, which completely remove a gene or dramatically up-regulate it). Not wishing to show any mammalian bias, they did the same thing in flies. In all cases, the results were consistent with the human data–the low-sleep allele led to increased activity in both species.
Out of curiosity, is 6 hours of sleep (without an alarm clock) really all that odd for people? It certainly would be for me, but I feel like I know plenty of people who claim to naturally need only about that much.
Labels: Genetics
I’m not sure if it’s that much to me? When I was in college, I slept six hours a night and felt fine. Now I’m a little older and find myself getting 7-8 hours. I’m not sure if that’s just because I’ve gotten used to sleeping longer or if I need more; I wake up at 7AM naturally, regardless of when I went to bed.
Also, I’m kind of a night owl and work best at night. Whenever I wake up I feel like crap for the first few hours I’m awake, regardless of how rested I am. But I never have any problems getting up! The snooze button is for wimps.
as adam says, this varies across one’s life. additionally, i think there is currently a cultural bias to underemphasize how much sleep you need (real men & pardis sabeti don’t sleep :-). finally, speaking from personal experience 6 hours is fine in terms of functioning for many days at a time (especially with coffee, etc.), but it seems that after a while i really start wanting a “catch up” day. several years ago when i was working long hours but still wanted to blog & read i regularly slept less than 6 hours m-f, but made sure to catch up on the weekends (or on sunday if i was working 6 days).
from what little i’ve read though this sort of behavior has a long term negative effect on your health, so i try to be less of a man now :-) though i’m not sure if issues of causation have been well explored (i.e., those who sleep too little and too long tend to die earlier, but they might be messed up to begin with). i’m sure most people are aware of intrafamilial variation. my mother and her father require (or required in his case) less uninterrupted sleep than seems the norm (he lived to 100, so it didn’t kill him early).
I must carry the extra-sleepy allele…
Does anyone get how they selected candidate genes?
Does anyone get how they selected candidate genes?
they say in the supplement they were screening all circadian clock-related genes (a number of these have been identified in, eg. mutagenesis screens in various organisms).
Out of curiosity, is 6 hours of sleep (without an alarm clock) really all that odd for people?
I did that for about 5 years when I had to get up at 5 a.m. I couldn’t stand to go to bed and often stayed up until 11, always until 10.
No alarm clock: I used an alarm clock for the first year or so, but I hated the sound so much that I learned to wake up immediately before it rang. After awhile I stopped even setting it. (My son can do this too). I once got home at 3 a.m. and slept for 2 hours without an alarm clock, and then went to work.
Starting about age 45 I’ve needed more sleep, while at the same time having more problems sleeping. Growing old is better than the alternative, but……
In what can only be described as a ballsy move, the authors then invested what must have been a considerable amount of time and money on following up this mutation. Which, I emphasize again, was found in only two individuals in a single family.
Publication bias. You never hear from those with ballsy moves that generated nothing. Which is why those in the beginning of their careers cannot afford anything risky and have to make their names doing boring predictable stuff first.
I’ve got problems going to sleep so I rarely get 8 hours. When I was in college I had one class that was at 9 on Thursday mornings, so the Wednesday night before I’d drink a cup of bourbon to help knock myself out.
I am a physician and from the research I’ve read, the optimal amount is between 9 and 9.5 hours per night, actually. If you are getting less than 8, you’ll acquire sleep debt. Obviously there is variation, and there is also variation in falling asleep, although those taht have trouble falling asleep probably don’t sleep well either. In medical school i realized that a LARGE portion of my classmates told me they would take anywhere from 30 min to an hour to fall asleep, just sorta “hanging out” in bed. That was WEIRD, I thought. I’m done in 2 minutes at the most. There might be something to that link. Who knows.
Regardless of what you “require” it’s my belief that if you don’t get 8+ you won’t function as well as you otherwise could. And yes, coffee masks a ton, you hit it on the head, Razib
I’m at my best on nine hours of sleep.
I’m seldom at my best.
I usually sleep 5 to 6 hours a night m-f and sleep in on Saturday morning (7-8 hours), but might only get 4 hours on Sunday night. I have had problems falling asleep since as far back as I remember. I also have problems waking up, and am like a zombie in the morning for the first 30 minutes and sleepy for about 2 hours. I have to eat before I shower, even if running late for work, in case I fall over in the shower. I have been known to sleep through an alarm clock on max volume, both beeping or radio, for as long as an hour. I especially find it hard to sleep on nights when it rains, even if it is very light rain, for whatever reason, but not because of the noise of the rain…
I used to drink 2-3 cups of coffee a day to stay awake and focused, but cut it down to one cup on the advise of a girlfriend – as she said it was keeping me awake – but to no effect. So after seeing that I was a very fast caffeine metabolizer – based on 23AndMe results – have gone back to 4 cups a day, and if anything find that it helps a little, in that it makes me more productive during the day and so slightly more tired and capable of sleeping at night.