Night owl
Kim Carney / msnbc.com
By
msnbc.com contributor
updated 5/29/2009 7:45:35 AM ET 2009-05-29T11:45:35

For years Deborah Africa would stay up late and sleep in, savoring every extra second of sleep before dragging herself out of bed by 10 a.m. When Africa had kids and switched to an earlier schedule, she thought getting up four hours earlier might make for a tough adjustment. But she soon noticed a subtle change in her mood: the new schedule seemed to make her a little more energetic and optimistic.

“Sometimes I still feel like it might be nice to stay in bed and lounge about,” says the 56-year-old nurse from Morgan Hill, Calif. “But when I wake up on this early schedule I feel like I’ve got the whole day in front of me with plenty of time to do everything I need to get done.”

A new study, published in Psychiatry and Clinical Neurosciences, bears out Africa’s experience: People who tend to stay up late, the so-called "night owls," have a darker outlook than those who bounce out of bed at the crack of dawn, the “morning larks.” 

Brazilian researchers chose to scrutinize people’s sleep/wake schedules because depression has been shown to wreak havoc on sleep, notes the study’s lead author, Dr. Maria Paz Loayza Hidalgo of the Universidade Federal do Rio Grade do Sul in Porto Alegre. Further, Hidalgo explains, studies have shown that some depressed patients can be helped by light therapy. For this type of therapy, patients attempt to reset sleep schedules distorted by depression by sitting in front of a bright light for two hours first thing in the morning.

For the new study, they randomly selected 200 healthy people with no history of mental illness and asked them about their sleep habits and depression symptoms. They found that night owls were almost three times as likely as morning larks to experience severe symptoms of depression. Even more striking was the comparison with people who went to bed at an intermediate time. Compared to them, night owls were five times as likely have severe symptoms.

On average, the differences in bedtime weren't huge. Night owls turned in around midnight, while morning larks went to bed around 11 p.m.  The same was true of rising time: night owls awoke 40 minutes, on average, later than larks. Length of sleep was about the same for the two groups.

“The study shows that even relatively subtle shifts in patterns of sleep seem to make a big difference in how people rate their mood,” says Dr. Ian A. Cook, an associate professor of psychiatry at the University of California, Los Angeles, and director of the university’s Depression Research & Clinic Program. “That’s very intriguing stuff. Like any good study, it raises many more questions than it answers.”

What we don’t yet know is whether the sleep schedule is causing the depression symptoms or whether feelings of sadness and worry are keeping people up late, Cook says.

Still, the study suggests that it might be possible to brighten your mood by changing your schedule, Cook adds. If you want to experiment with this, Cook suggests buying a second alarm clock and setting it for your targeted bed time as a reminder that it’s time to go to sleep.

Another tip: avoid stimulating activities close to your new bedtime, says Dr. Alan Manevitz, a psychiatrist at New York-Presbyterian Hospital/Weill Cornell Medical Center. In particular, Manevitz suggests skipping the late night email check — besides anxiety that can come from reading distressing messages, the light from your computer monitor may wake you up a bit.

Not so easy?
Some experts believe that sleep schedules and the tendency to depression might not be so mutable.

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Scientists have found genes that cause some people to prefer to rise early and others to sleep late, says Dr. Eric Nofzinger, a professor of psychiatry and director of the sleep neuroimaging research program at the University of Pittsburgh School of Medicine.

We may be seeing some innate differences in brain wiring that keep night owls more revved up in the evening and that make them more prone to depression, Nofzinger says.

Using a PET scanner to peer into the heads of depressed patients, Nofzinger has discovered that their brains function differently during sleep than those of others. Depressed patients show much more activity in parts of the brain that are involved in processing and experiencing emotion, Nofzinger says. And because of this, they never get a good, restorative night’s sleep.

Like father, like daughter
John Musumeci isn’t surprised to hear that sleep schedule might impact mood.

Musumeci has always been a morning person. As soon as the first ray of sun slants through his window he’s bounding out of bed, happy to get a jump on his day, knowing that those early hours are the ones that will be the most productive.

“My wife is just the opposite,” says the 57-year-old store owner from Alloway, N.J. “And she’s a little darker in disposition. Not all doom and gloom — just not as chipper as I am. My daughter takes after me. She gets up early and is fairly chipper.”

While some people may be saddled with genes that make it hard for them to get to bed earlier, many may simply be responding to the lure of modern life’s late night options, says Cook.

“This study raises the question of what happens in a world of 24-hour news cycles that tempt people to stay up late,” he adds. “That could create a tendency to drift into the night owl pattern which could create a risk for developing mood problems.”

Linda Carroll is a health and science writer living in New Jersey. Her work has appeared in The New York Times, Newsday, Health magazine and SmartMoney.

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