Our circadian rhythms are synchronized to the 24-hour light-dark cycle, are passed down through our genes, and typically last about 24 hours. The best sleep occurs when your circadian rhythm matches the timing of your sleep. When sleep and wake cycles are disrupted for whatever reason, the circadian rhythm becomes disturbed. 

The American Academy of Sleep Medicine (AASM) defines a CRSWD as being “caused by alterations of the circadian time-keeping system, its entrainment mechanisms, or a misalignment of endogenous circadian rhythm and the external environment.”¹ What does that mean? It means that your body’s internal clock is off, either because it’s not working properly, it’s not syncing with daily cues like light and dark, or it’s out of sync with your daily schedule. CRSWDs are diagnosed based on history, the results of actigraphy, and the review of a symptom diary  (kept for at least 7, but preferably 14, days). The most common CRSWDs include the intrinsic CRSWDs—delayed and advanced sleep-wake phase disorder (DSPD and ASPD, respectively)—and the extrinsic CRSWDs—shift work disorder (SWD) and jet lag disorder (JLD). Intrinsic CRSWDs happen when your body’s internal clock is out of sync due to some factor within your body. Extrinsic CRSWDs are caused by things outside of your body that throw off your sleep-wake schedule.

CRSWD General Diagnostic Criteria¹

The ICSD-3-TR criteria for CRSWD include three that apply to all CRSWD and assume a problem with sleep or wakefulness. These general criteria include the following:

Criteria A-C must be met

1. A chronic or recurrent pattern of sleep-wake rhythm disruption, primarily due to alteration of the endogenous circadian timing system or its entrainment mechanisms, or to misalignment between. The endogenous circadian rhythm and the sleep-wake schedule desired or required by an individual’s physical environment or social/work schedules.
2. The circadian rhythm disruption leads to insomnia symptoms, excessive sleepiness, or both.
3. The sleep and wake disturbances cause clinically significant distress or impairment in mental, physical, social, occupational, educational, or other important areas of functioning.

Intrinsic CRSWD

Delayed Sleep-Wake Phase Disorder 

DSWPD is especially common in teens and young adults—so if you find yourself (or your teenager) wide awake late at night and struggling to get up in the morning, you’re definitely not alone. Most people with DSWPD don’t have trouble staying asleep—they just can’t fall asleep until much later than what’s considered “normal.” The problem is, life doesn’t always match that schedule. School, work, or early commitments can force you to wake up before your body’s ready, leading to sleep loss and exhaustion. And things like bright lights at night can make it even harder to shift your sleep earlier.

DSWPD Diagnostic Criteria¹

Criteria A–E must be met

1. There is a significant delay in the phase of the major sleep episode in relation to the desired or required sleep-onset time and wake-up time, as evidenced by:
   1. A chronic or recurrent complaint by the patient or a caregiver of inability to fall asleep at the desired or required time; and
   2. Difficulty awakening at the desired or required clock time.
   3. The symptoms have been present for at least three months.
2. When patients are allowed to choose their ad libitum schedule, they will exhibit improved sleep quality and duration for age and maintain a delayed phase of the 24-hour sleep-wake pattern.
3. Sleep logs are required, accompanied by actigraphy monitoring whenever possible, for at least seven days—preferably 14. These demonstrate a delay in the timing of the habitual sleep period. Both work/school days and free days should be included in this monitoring.
4. The sleep disturbance is not better explained by another current sleep disorder, medical disorder, mental disorder, or medication/substance use.

Advanced Sleep-Wake Phase Disorder

If you find yourself getting really sleepy way earlier than everyone else—like nodding off in the early evening—and then waking up hours before your alarm, you might be dealing with ASWPD. It’s not that you’re not getting enough sleep—once you’re out, you usually sleep just fine. The challenge is that your body’s clock is running ahead of schedule. So even if you try to stay up later for social plans or evening activities, you still wake up super early, which can leave you feeling tired and out of sync with the rest of the world and leading to a cycle of sleep loss.

ASWPD Diagnostic Criteria¹

Criteria A–E must be met

1. There is a significant advance (earlier time) in the phase of the major sleep episode in relation to the desired or required sleep-onset time and wake-up time, as evidenced by:
   1. A chronic or recurrent complaint by the patient or a caregiver of difficulty staying awake until the required or desired conventional bedtime; and
   2. Difficulty remaining asleep at the required or desired time for awakening.
2. The symptoms have been present for at least three months.
3. When patients are allowed to choose their ad libitum schedule, they will exhibit improved sleep quality and duration and maintain an advanced phase of the 24-hour sleep-wake pattern.
4. Sleep logs are required, accompanied by actigraphy monitoring whenever possible, for at least seven days—preferably 14. These demonstrate a stable advance in the timing of the habitual sleep period. Both work/school days and free days should be included in this monitoring.
5. The sleep disturbance is not better explained by another current sleep disorder, medical disorder, mental disorder, or medication/substance use.

Extrinsic CRSWD

Shift Work Disorder

If you’ve ever worked a night shift, rotating schedule, or had to be on call overnight, you know how tough it can be on your sleep. For some people, these schedules don’t cause much trouble, but for others, they can really throw off the body’s natural rhythm. You might feel extremely sleepy while you’re supposed to be awake, or find it nearly impossible to get satisfying sleep when you’re finally off the clock. This is known as SWD, and it’s more common than you might think. Sleep often feels short and low-quality, and over time, that can affect your focus, mood, and even safety—especially when driving home after a long night shift. Approximately 20% of people are involved in shift work, with an estimated 30% of them having SWD.²

SWD Diagnostic Criteria¹

Criteria A-D must be met

1. There is a report of insomnia or excessive sleepiness, accompanied by a reduction of total sleep time, which is associated with a recurring work schedule that overlaps the usual time for sleep.
2. The symptoms have been present and associated with the shift work schedule for at least three months.
3. Sleep logs are required, accompanied by actigraphy monitoring whenever possible (preferably with concurrent light exposure measurement) for at least 14 days (work and free days). These demonstrate a disturbed sleep-wake pattern.  
4. The sleep disturbance is not better explained by another current sleep disorder, medical disorder, mental disorder, inadequate sleep hygiene, or medication/substance use.

Jet Lag Disorder

If you’ve ever taken a long flight across a few time zones—especially heading east—you’ve probably felt the effects of jet lag. That groggy, out-of-sync feeling, trouble falling asleep at night, and struggling to stay awake during the day? That’s JLD in action. It happens because your body’s internal clock is still set to your home time, even though your surroundings have changed. The more time zones you cross, the more intense and longer-lasting the symptoms can be.¹ It’s frustrating, especially when you’re trying to enjoy a trip or jump right back into work after traveling. 

JLD Diagnostic Criteria¹

Criteria A-C must be met

1. There is a report of insomnia or excessive sleepiness, accompanied by a reduction of total sleep time, associated with transmeridian jet travel across at least two time zones. 
2. There is associated impairment of daytime function, general malaise, or somatic symptoms (eg, gastrointestinal disturbance) within one to two days after travel.
3. The sleep disturbance is not better explained by another current sleep disorder, medical disorder, mental disorder, or medication/substance use.

The Treatment of CRSWD

Living with a CRSWD can feel like being out of sync with the world around you—when your body’s internal clock doesn’t match the rhythm of daily life, even simple routines can become overwhelming. But there is hope. Advances in sleep medicine are offering new paths to relief and, more importantly, to restoration.

Treating CRSWDs often starts with helping the body’s internal clock get back in sync. This usually means adjusting when someone is exposed to light—either earlier or later in the day—depending on whether their sleep cycle needs to shift forward or back. Melatonin can also play a helpful role when taken at the right time, and setting consistent sleep and wake times that better match the natural 24-hour rhythm is often part of the plan.

That said, the latest guidelines from the AASM highlight that there’s still a lot we’re learning. For example, the AASM doesn’t currently make strong recommendations for using planned sleep schedules or light exposure alone to treat intrinsic CRSWD. For ASWPD, they only give a cautious, or “weak,” recommendation for light therapy. Similarly, for DSWPD, using timed melatonin is also considered a weak recommendation.³ This means these treatments might help some people, but the evidence isn’t strong enough yet to say they work for everyone.

For people dealing with CRSWDs of SWD and Jet Lag Disorder JLD, the AASM provides additional recommendations.⁴ If you work night shifts, taking a short nap before or during your shift can help you stay more alert. Getting the right kind of light at the right time—like bright light during your shift and avoiding light in the morning—can also help reset your body clock. Some people benefit from taking melatonin before trying to sleep during the day or using sleep aids to help them rest. Medications like modafinil may be used to boost alertness during work hours, hypnotic medication used to promote daytime sleep, and caffeine use during your night shift are options. 

For JLD, the only strong recommendation for treatment is to take melatonin at the right time ⁴; there are also other helpful recommendation options, depending on your travel plans:

• Short trips (1–2 days)? Try sticking to your usual sleep and wake times from home while you travel. It might feel a little off, but it can help avoid the full effects of jet lag.
• Traveling east? Try getting some morning sunlight and gradually shifting your bedtime earlier—about an hour earlier each night for a few days before you leave. This can help your body start adjusting before you even board the plane.
• Having trouble sleeping? A short-term sleep aid might help you get the rest you need while your body adjusts.
• Feeling groggy during the day? A little caffeine can help you stay alert, just be mindful of the timing so it doesn’t interfere with your sleep later.

Everyone’s body reacts a bit differently, so it might take some experimenting to find what works best for you. But with a little planning, jet lag doesn’t have to ruin your trip.

References

1. American Academy of Sleep Medicine. International Classification of Sleep Disorders, 3rd ed, Text Revision. American Academy of Sleep Medicine; 2023.
2. Moreno CRC. Shift work sleep disorder. Handb Clin Neurol. 2025;206:89-92.
3. Auger RR, Burgess HJ, Emens JS, Deriy LV, Thomas SM, Sharkey KM. Clinical practice guideline for the treatment of intrinsic circadian rhythm sleep-wake disorders: advanced sleep-wake phase disorder (ASWPD), delayed sleep-wake phase disorder (DSWPD), non-24-hour sleep-wake rhythm disorder (N24SWD), and irregular sleep-wake rhythm disorder (ISWRD). An update for 2015: an American Academy of Sleep Medicine clinical practice guideline. J Clin Sleep Med. 2015;11(10):1199-1236..
4. Morgenthaler TI, Lee-Chiong T, Alessi C, et al. Practice parameters for the clinical evaluation and treatment of circadian rhythm sleep disorders. Sleep. 2007;30(11):1445-1459.