Our previous post explored the chicken-and-egg problem: What comes first, depression or insomnia? Should we target insomnia in the treatment of depression? Now we go further and compare insomnia treatment methods: Do they serve the same ends, by the same means?

New York Times writer Benedict Carey reports preliminary data showing that the combination of antidepressant meds and cognitive behavioral therapy for insomnia (CBT-I) greatly exceeds either one in speeding relief from depression. The Times editorial board mirrors his story with a strong endorsement: “This could be the most dramatic advance in treating depression in decades.”

Surprising? In a broader context, we’re reminded of the classic finding that psychotherapy + antidepressants works better than either one alone. What’s different here? We would say that CBT-I, like the similar approaches of old-fashioned sleep hygiene, and interpersonal and social rhythm therapy for bipolar depression, provides a diluted mimic of chronotherapy. (The Times describes sleep hygiene incorrectly, as if it did not guide a regular sleep-wake schedule.) Chronotherapy delivers enhanced light exposure upon scheduled awakening, and instructs reduced short-wavelength light exposure in the evening and darkness in the bedroom during sleep.

Under CBT-I, you aim essentially to stabilize the morning light synchronizer for your circadian cycle by waking up on a regular schedule. The CBT-I effect is therefore indirect. By contrast, chronotherapy directly provides the synchronizer, enhanced for rapid response by anchoring treatment time to the patient’s underlying circadian rhythm. In so doing, it has the added advantage of reducing reliance on antidepressant meds.

The Times reports faster recovery from depression for patients who resolved their insomnia, but does not indicate the proportion of patients whose insomnia persisted or was exacerbated. There is a distinct risk to the “therapeutic” instruction to wake up consistently early (and receive morning light) if a patient has marked delayed sleep phase insomnia  for example, is unable to fall asleep until 2:30 AM, but requiring 7:00 AM wake-up to meet the daily work schedule.

After less than five hours of sleep, the circadian cycle is deep into its nighttime mode, even if the sun has risen outdoors. Apart from the obvious problem of sleep deprivation, light exposure at this point further delays the inner clock, or prevents it from shifting earlier. This is a common pitfall of unsupervised self-treatment, not to mention therapy supervised by clinicians who do not understand how the circadian timing system can respond bi-directionally. Awakening under CBT-I, like under light therapy, should be introduced no earlier than one hour before the end of the circadian night, after which it can be shifted gradually earlier. The circadian night can be conveniently gauged using our online chronotype questionnaire, with feedback pinpointing a safe starting point for wake-up into light.