CBT raised the patients' average slow-wave sleep 27% by the end of treatment, and had increased it 34% six months later.
On the other hand, patients who took the sleeping pill had a big drop in the amount of slow-wave sleep they got. They had 20% less slow-wave sleep at the end of treatment. Six months later, they had 23% less slow-wave sleep.
"That is scary, when you see that lack of slow-wave sleep is responsible for most daytime sleepiness," Sivertsen says. "And there is an ongoing debate in the American media about traffic-related incidents with sleeping pills."
Simon isn't totally convinced by the finding.
"For most of the newer sleep medications, investigators have found no decrease in [slow-wave] sleep," he says. "But with the older drugs, like Halcion, that is a common finding."
"We were quite surprised to find that [Imovane] decreased slow-wave sleep," Sivertsen says. "The manufacturer says [Imovane] increases slow-wave sleep. We found the opposite. True, we had a relatively small number of patients. But all the patients in the placebo arm were randomized to get one of the two treatments. If we put those additional patients into the final analysis, we get even larger effects. The findings were still there and still significant."
How CBT Cures Insomnia
The CBT used by Sivertsen and colleagues consists of six hour-long sessions one week apart. The sessions incorporate five principles:
- Sleep hygiene. Patients learn how lifestyle habits (such as diet and alcohol use) and environmental factors (such as light, noise, and temperature) affect sleep.
- Sleep restriction. Patients keep to a strict schedule of bed times and wake times that at first increases their sleepiness by depriving them of sleep.
- Stimulus control. Patients learn to associate being in bed with going to sleep. They learn not to do anything in the bedroom that does not help them sleep.
- Cognitive therapy. "The thoughts people with insomnia have about sleep are a bit skewed," Sivertsen says. "Cognitive therapy gives patients control over what is going on. They become their own co-therapists."
- Progressive relaxation technique. Patients learn to recognize and control muscular tension.