Delayed sleep phase disorder
| Delayed sleep phase disorder | |
|---|---|
| Other names | Delayed sleep–wake phase disorder, delayed sleep phase syndrome, delayed sleep phase type, social jet lag |
| Comparison of standard (green) and DSPD (blue) circadian rhythms | |
| Specialty | Sleep medicine, neurology, psychiatry |
| Symptoms | Delayed sleeping times (usually after midnight), resistant to conscious attempts to change, potential occasional bouts of insomnia, extreme jet lag-like effects |
| Complications | Severe cases can be disabling from a social and occupational perspective. DSPD can aggravate other medical issues that often worsen from sleep issues or stress, such as psychiatric disorders |
| Duration | Usually chronic if symptoms occur/persist past adolescence |
| Causes | Genetics, traumatic brain injury (secondary) |
| Risk factors | Attention deficit hyperactivity disorder, long COVID, traumatic brain injury (secondary) |
| Diagnostic method | Debated, a consistent inability to change the late sleep cycle for a certain period of time needs to be demonstrated during a clinical interview and or a sleep diary, polysomnography, and actigraphy can also be used. The ICSD criteria are often used. |
| Differential diagnosis | Other parasomnias, symptoms that are part of much greater psychiatric/neurological issues |
| Prevention | Secondary causes from brain injuries can be mitigated by PPE |
| Treatment | Light therapy, darkness therapy, moving important tasks to earlier times, gradually shifting to earlier bedtime and waking times, medication for augmentation or monotherapy |
| Medication | Melatonin, ramelteon, aripiprazole (in low doses), agomelatine, modafinil (for eugeroic effects) |
| Prognosis | Milder cases (those with earlier sleeping times) have a higher rate of remission and a longer time until relapses start after treatment is discontinued. Prognosis is generally poorer in severe cases and those who do not or cannot seek treatment. |
| Frequency | Exact estimates are unreliable due to varying definitions of DSPD, though it is generally accepted that it is more common in adolescents. |
Delayed sleep phase disorder (DSPD), more often known as delayed sleep phase syndrome and also as delayed sleep–wake phase disorder, is the delaying of a person's circadian rhythm (biological clock) compared to those of social norms. The disorder affects the timing of biological rhythms including sleep, peak period of alertness, core body temperature, and hormonal cycles. People with this disorder are often called "night owls". It is considered to be a category of circadian rhythm sleep disorder.
The diagnosis of this disorder is currently a point of contention among specialists of sleep disorders. Many insomnia-related disorders can present significantly differently between patients, and circadian rhythm disorders and melatonin-related disorders are not well understood by modern medical science. The orexin system was only identified in 1998, yet it appears intimately implicated in human sleep-wake systems.
Evidence for the plasticity of human circadian rhythm cycles has been provided by multiple studies. In one example, 15 volunteers spent 40 days and nights underground in a French cave while researchers monitored their periods of waking and sleeping. Their results found significant divergence between individuals, with most participants settling upon a rhythm of 30 ± 4 hours. Researchers have speculated that the lack of exposure to natural sunrise/sunset cycles relates many of the symptoms of these circadian disorders to modern habits of humans spending extended periods indoors, without sunlight exposure and with artificial light.
Symptom management may be possible with therapeutic drugs such as orexin antagonists or melatonin receptor agonists, as well as regular outdoor exercise. There may be a genetic component to the syndrome.