Ask the doctors: Delayed sleep cycle linked to range of health problems

Dear Doctor: My mother and my sister are both night owls who stay up late and sleep late the next morning. In our family we never thought anything of it. But now it turns out their sleeping habits are something called “delayed sleep phase disorder.” Why is being a night owl considered to be a disorder? Can it be cured?

Dear Reader: Although in the past the sleep cycle you’ve described was called a disorder, it is now more often referred to as a syndrome. Specifically, it’s when someone’s sleep cycles are delayed by two or more hours, which puts the individual out of step with the majority of the people around them.

It was once believed that being a night owl was simply a preference, or perhaps even a psychological issue, but new research ties it to the workings of the individual’s body clock, or more specifically, circadian rhythm. This is an internal system that regulates not only the cycle of sleep and waking, but also a range of metabolic functions that include body temperature, hormone secretion, digestion and even wound healing. The master body clock oversees circadian rhythms, which are influenced by factors within the body. Circadian rhythms are also are tied to the cycles of light and dark as the sun rises and sets.

Someone with delayed sleep phase syndrome, or DSPS, is unable to fall asleep at the typical bedtime of 9, 10 or 11 p.m. Instead, these individuals often report that when the rest of the world is nodding off, they are coming to life. Staying up until the early morning hours shifts their optimal time of awakening as well.

But due to real-world responsibilities like work, school and family, people with DSPS are often forced to rise long before they get an adequate amount of sleep. This leads to daytime drowsiness; it has also been linked to depression. A recent study, which analyzed the sleep habits of 430,000 adults for 6 1/2 years, found that so-called night owls were more likely to develop diabetes and neurological disorders. It also found a 10 percent increase in premature death when compared to early-to-bed sleepers.

The good news is that, other than the time shift, people with DSPS don’t usually have other sleep issues such as interrupted sleep or insomnia. When left to their own devices, they go to bed late, sleep well, then rise late, feeling refreshed.

For those who want to switch to more traditional sleep habits, a number of treatments have proven effective. The challenge is that not everything works for everyone, so a period of experimentation is often required, often with the help of a sleep specialist. Approaches include bright light therapy, which is believed to shift the circadian clock. Another is phase-delay chronotherapy, in which bedtimes are set progressively later until, at the end of a set period of time, the desired bedtime has been reached. The theory here is that adjusting to a later bedtime is easier than to an earlier one. Medications like melatonin can be helpful, and some people use sleep aids when they hit a rough patch. The important thing in all of these approaches is consistency.