Sleep and Sleeeep

When it comes to sleep, I think the years in college would be a good time to measure how much sleep one needs. Were you one of those who can study (or for some, party) through the night and into the morning and still stay alert to take tests? Or were you one of those whose bodies agreed with the “study habits” manual that says we should have a full night’s sleep which meant about eight hours? It turns out that the hours of sleep you required may depend on what your parents have given you.

Through a recent study, science has just given you reason to blame or thank your parents for: the amount of sleep you need. No, they did not condition you by requiring or not requiring that you have those naps in the afternoon. They may have passed on a genetic mutation to you. The gene is called DEC2 and if you have it, you would need less sleep than others who do not have that mutation.

The new study that you can show your parents appeared in the Aug. 14 issue of the journal Science. It is entitled The Transcriptional Repressor DEC2 Regulates Sleep Length in Mammals and authored by Ying He, Christopher R. Jones, Nobuhiro Fujiki, Ying Xu Bin Guo, Jimmy L. Holder Jr., Moritz J. Rossner, Seiji Nishino and Ying-Hui Fu. They were testing many subjects until they came across a mother (aged 69) and her daughter (aged 44) who consistently slept less compared to the others which meant a total of five-and-a -half hours compared to seven to eight hours for most. They identified this mutation and even carried it further by again commissioning mice to carry that mutation to see if they would really sleep less than those who they did not give the mutation to. It checked out with the mice — the ones who had the mutation slept less but this did not affect the way they scored on maze tests.

It intrigues me that it is a mother and her daughter who had that mutation and not males. I would be interested to know if the activation of this mutation is gender-specific. Now why would females ever need less sleep and evolve to still be reliably sharp when we obviously have had men who have been doing such a marvelous job in managing human affairs while consistently holding on to late nights? Wake me up when you come up with an interesting answer.

This mutation, by the way, does not refer to “night owls” — those who feel more alert at nighttime but require as much sleep in the daytime. The people with the DEC2 mutation have “normal” body clocks but they sleep for shorter periods. As science so far is able to share with us, human sleep seems to be influenced by that inner “clock” (when we fall asleep and wake up) and “homeostasis” which is supposed to influence how much sleep we need. The scientists think the gene affects both although they do not yet know how the mutation does this. They just know that when people have this mutation, they doze off for shorter periods than most and function no less. Scientists think that the mutation is rare because it appeared only in the mother and daughter among 250 subjects.

I am curious as to how this mutation evolved. What conditions could have made it necessary for some humans to sleep less and still function normally? I would have bet on “having children” as the number one reason, except that it is obviously not a rare condition. Having this mutation does influence how much easier it is for people especially for professional drivers, security personnel or maybe sleep scientists to manage their sleep-wake times. I listened to an interview in NPR with one of the scientists herself who did the study, Ying-Hui Fu, where she cheerfully wished that she had the mutation but said that she really needs normal sleep length in order to function properly. But nature is slow and “blind” in the way it does mutations — we cannot have them by simply wishing them.

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