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Looking to catch up on the latest discussions and research in the world of shuteye? I've got you covered. Here's this week's Nightcap:

Lark, owl, repeat   

It's normal for your chronotype to change a few times during your lifetime: We tend to start out as early birds, turn into teenage night owls and then rediscover the joys of the morning during adulthood. But, of course, circadian rhythms vary widely. Some teenagers still hit the sack at a reasonable-ish hour. And some adults never learn to love rising with the sun. And a new study, lead by Harvard researchers, showcases just how much chronotypes vary, both over time as well as between people. The study was based on data submitted by more than 50,000 people who responded to the American Time Use Survey between 2003 and 2014. Researchers used weekend sleep mid-point as a proxy for chronotype. They found that chronotype peaks in lateness around age 19 and that, in any given age group, chronotypes vary by up to 10 hours from person to person. [PLOS]

Are you the same person when you're asleep and awake?   

When Tanya, a woman with a dark past, listens to recordings of herself sleep-talking, she hears a giggly, innocent girl she doesn't recognize. To reconcile her contradictory dreaming and waking selves, Tanya tries her hand at "dream incubation," a technique used to guide dreams towards a specific topic. [NPR's Invisibilia]

Obsess the night away

Night owls appear to have less control over obssessive thoughts than their morning-oriented counterparts, according to a new study from SUNY Binghamton. For the study, participants with diagnosed OCD, and subclinical OCD symptoms, kept sleep diaries for a week. They also provided daily ratings of their (perceived) levels of control over obsessive thoughts and compulsive behaviors. Later bedtimes, researchers found, were significantly associated with less control over OCD symptoms the following day. The research was presented earlier this month at the 2017 SLEEP conference. (Check out this research recap for more studies from the conference.) [Neuroscience News]  

A refresher on dream science

Freudian's perspective on dreams — as the symbolic expression of repressed desires and fears — dominated psychology for the better part of a century. But in the past 30 years, researchers have largely left Freud behind in their efforts to understand the nature, function and content of dreams. Experts still don't know, with certainty, why we dream, but they've learned a lot about when we dream, what we dream about, what goes on in our brains during our REM adventures and how dreaming facilitates processes including memory and early cognitive development. [NPR

Saturdays are for sleeping in 

A new study from the University of Colorado found that sleeping in for two days helped un-do some of the damage from short-term sleep deprivation. In this case, the damage manifested as decreased insulin sensitivity (which is linked to diabetes risk) that researchers observed after participants had slept 4.5 hours a night, for four consecutive nights. But, after getting almost 10 hours of sleep for two nights in a row, participants' insulin sensitivity rebounded. "It gives us some hope that if there is no way to extend sleep during the week," said lead study author Josaine Broussard, "people should try very hard to protect their sleep when they do get an opportunity to sleep in and sleep as much as possible to pay back the sleep debt." [Reuters]

Sleep apnea contributed to Carrie Fisher's death

Last Friday, the Los Angeles County Medical Examiner's Office revealed that sleep apnea played a role in the death of Carrie Fisher. The actor and outspoken mental-health advocate passed away last December at 60, four days after suffering a heart attack on a flight from London to Los Angeles. Sleep apnea was one of several contributing factors in Fisher's death, the official cause of which was "undetermined." It's not clear whether or not Fisher knew she had sleep apnea, a sleep-breathing disorder that is thought to be under-diagnosed in women. [Chicago Tribune]