Our bodies follow an internal biological clock known as the circadian
rhythm, which regulates when we feel awake and when we feel sleepy.
This internal clock is influenced primarily by light exposure, and it helps
coordinate many important functions including sleep, hormone release,
metabolism, and body temperature.
Circadian rhythm disorders occur when the body’s internal clock becomes
misaligned with the desired sleep schedule. As a result, individuals may
struggle to fall asleep at the appropriate time, wake at the desired hour, or
feel rested during the day.
These disorders are common but often overlooked causes of chronic sleep
difficulty and daytime fatigue.
Common Types of Circadian Rhythm Disorders
Delayed Sleep Phase Disorder
In delayed sleep phase disorder, the body’s natural sleep cycle is shifted
later than normal. Individuals may not feel sleepy until very late at night,
often after midnight or even early morning hours.
Despite this late sleep timing, they still need to wake early for work or
school, leading to chronic sleep deprivation.
Advanced Sleep Phase Disorder
In advanced sleep phase disorder, the sleep schedule is shifted earlier than
normal. Individuals become sleepy very early in the evening and wake up
very early in the morning.
This pattern is more common in older adults.
Irregular Sleep-Wake Rhythm
Some individuals have a fragmented circadian rhythm with no consistent
sleep schedule. Sleep may occur in multiple shorter periods throughout
the day and night rather than one consolidated sleep period.
Shift Work Sleep Disorder
People who work night shifts or rotating shifts may experience difficulty
maintaining a stable sleep schedule because their work hours conflict with
the body’s natural circadian timing.
This can lead to fatigue, insomnia, and difficulty staying alert during work
hours.
Symptoms of Circadian Rhythm Disorders
Symptoms vary depending on the type of circadian rhythm disruption but
may include:
● Difficulty falling asleep at the desired time
● Difficulty waking in the morning
● Excessive daytime sleepiness
● Poor concentration or memory
● Fatigue despite adequate time in bed
● Trouble maintaining a consistent sleep schedule
These symptoms can significantly affect daily functioning, work
performance, and overall quality of life.
What Causes Circadian Rhythm Disruption?
Several factors can influence the body’s internal clock:
● Genetics
● Irregular sleep schedules
● Late-night exposure to screens and artificial light
● Shift work
● Travel across time zones
● Changes in daily routines
Because the circadian rhythm is highly sensitive to light, even small
changes in light exposure patterns can affect sleep timing.
How Circadian Rhythm Disorders Are Evaluated
Evaluation begins with a detailed review of sleep patterns, daily routines,
and symptoms. In some cases, a sleep diary or wearable activity
monitor may help track sleep timing over several weeks.
If other sleep disorders such as sleep apnea or insomnia are suspected,
additional testing may be recommended.
Treatment Approaches
Treatment focuses on gradually realigning the body’s internal clock with
the desired sleep schedule. This may involve:
Light therapy
Carefully timed exposure to bright light can help shift the circadian rhythm
earlier or later depending on the disorder.
Melatonin supplementation
When used at the appropriate time of day, melatonin may help adjust the
sleep cycle.
Sleep schedule adjustments
Gradually shifting bedtime and wake time can help retrain the body’s
internal clock.
Optimizing light exposure
Reducing evening screen exposure and increasing morning light exposure
can support healthier circadian timing.
When to Seek Evaluation
You may benefit from evaluation if you:
● Consistently cannot fall asleep until very late at night
● Struggle to wake at a desired time despite adequate time in bed
● Experience persistent daytime fatigue
● Work rotating or night shifts and have difficulty adjusting your sleep
schedule
Addressing circadian rhythm disruption can significantly improve sleep
quality, daytime alertness, and overall well-being.
Schedule a Consultation
If you are experiencing difficulty with sleep timing or persistent fatigue, a
consultation can help determine whether a circadian rhythm disorder may
be contributing to your symptoms and discuss strategies to improve sleep
and daily energy.