When people think about sleep problems, insomnia is usually what comes to mind first. But a fair number of the patients I see with sleep complaints aren’t dealing with insomnia in the classic sense — they’re dealing with a circadian rhythm disorder, where the body’s internal clock has drifted out of sync with the schedule they need to keep.
Your circadian rhythm is essentially your body’s internal clock. It governs not just when you feel sleepy or alert, but a range of other physiological processes, and under normal conditions it runs on roughly a 24-hour cycle that tracks the earth’s day-night pattern. When that rhythm gets disrupted, the result isn’t always trouble falling asleep at night — it can just as easily be trouble staying awake during the day, at the wrong times, in the wrong places.
What throws the clock off
The most common culprits are shift work, pregnancy, travel across time zones, certain medications, and any significant disruption to a person’s normal routine. Some people are more biologically prone to circadian drift than others, which is part of why two people can keep the same irregular schedule and only one of them develops a real disorder.
The patterns I see most often
- Jet lag — daytime sleepiness and reduced alertness after crossing time zones
- Shift work sleep disorder — difficulty adjusting to rotating or overnight shifts, often producing genuine insomnia
- Delayed sleep phase syndrome — falling asleep very late and struggling to wake for school or work
- Advanced sleep phase syndrome — the reverse: falling asleep and waking earlier than a person wants to
- Non-24-hour sleep-wake disorder — a cycle that runs closer to 25 hours than 24, producing inconsistent, shifting insomnia night to night
How these get treated
Before treating a circadian rhythm disorder as such, I want to rule out medication side effects and underlying medical conditions that can produce similar symptoms. Once that’s done, treatment usually combines a few approaches: behavioral changes — a consistent sleep and wake schedule, no naps, regular exercise, cutting caffeine and nicotine — along with more targeted interventions depending on the specific disorder. Someone with delayed sleep phase syndrome benefits from minimizing light exposure in the evening; someone with advanced sleep phase syndrome benefits from the opposite. Melatonin, wakefulness-promoting medications, or short-term sleep aids can help shift the cycle toward where it needs to be. In some cases I use chronotherapy, gradually moving a bedtime earlier or later over several weeks, or bright light therapy — controlled exposure to high-intensity light to help reset the internal clock.
Poor sleep isn’t a minor inconvenience. Left unaddressed, a circadian rhythm disorder can contribute to depression, substance use, and a general erosion of someone’s ability to function at work, in school, or at home. If your sleep schedule feels genuinely out of your control, that’s worth bringing to a professional rather than managing alone.