Diagnosing and Treating Circadian Sleep Disorders

A 23-year-old male complained of insomnia, had difficulty falling asleep at night, and continually arrived at work at 11:30 a.m. when the employer work day started at 8 a.m. Did this patient have depression, situational insomnia, obstructive sleep apnea with daytime hypersomnia, or a true circadian rhythm disturbance? Or did he simply prefer to start work at 11:30 a.m.? Did he have a disability or condition that required treatment, or did he simply prefer a later work shift? The answer to these questions determined the employer’s response to this patient and the documentation required by the employee when the employee maintained that he has a medical reason for not getting to work on time.

Types of circadian disorders
Circadian rhythm sleep disorder is a disturbance of the sleep-wake cycle clock. The suprachiasmatic nucleus of the hypothalamus is important in setting the circadian sleep-wake clock. Actigraphy, an easy measurement of wrist movement that correlates with sleep, can be used to document sleep. There are also other markers of the sleep cycle, such as core body temperature and melatonin levels.

There are six circadian rhythm sleep disorders:

• jet lag
• shift work sleep disorder
• free-running sleep disorder (rare, but has been described in blind patients)
• irregular sleep wake phase
• advanced sleep phase disorder (rare)
• delayed sleep phase disorder (DSPD)

In advanced sleep-phase disorder, the patient’s sleep set point is “early,” and a patient typically falls asleep between 4 and 6 p.m. only to awaken very early in the morning. In delayed sleep-phase disorder, the sleep set point is late and the patient typically cannot fall asleep until 4 to 6 a.m. How can an employer differentiate a true delayed sleep-phase disorder from severe insomnia, depression or malingering?

Rule out other disorders
The first step is to send the patient to see a sleep medicine specialist to check the markers of the circadian sleep clock. While researchers have measured core body temperature in the past, a more easily measured marker is the level of melatonin secreted by the Pineal gland. Both a hormone and marker, melatonin is an integral part of the sleep cycle. Additionally, it is a treatment that induces sleep. Less melatonin is secreted in the early morning because light suppresses it; it increases at night. There are now immunoassays that measure melatonin in the saliva and plasma and there is a melatonin metabolite (6-sulphatoxy melatonin) that can be measured in urine. With the understanding that non-steroidal anti-inflammatory drugs (NSAIDS), caffeine and beta-blockers alter melatonin levels, measuring its levels can ascertain if the patient has a circadian sleep-phase disorder. The doctor can use a polysomnogram to rule out sleep apnea and there are numerous depression questionnaires and scoring systems to diagnose or rule out depression.

Therapies for circadian disorders
Delayed sleep-phase syndrome and early sleep-phase syndrome are circadian rhythm disturbances treated with a combination of melatonin and phototherapy to correct the circadian pacemaker. More data on melatonin and phototherapy for delayed sleep-phase syndrome is available than for early sleep-phase syndrome. Each day the physician alters the "pathologic" awake and sleep set times an hour until the awake-sleep cycle fits the socially desired schedule. To adjust the morning wake time, the doctor uses melatonin to induce the patient’s sleep in combination with bright light treatment at 2,500 lux for two to three hours. The phototherapy unit is the standard of care for this disturbance. The patient can purchase or rent one until the sleep-wake cycle is "corrected" for the desired schedule. The FDA has not approved melatonin, but it is available in the United States as a “supplement” in doses of 0.5 mg to 5 mg. A dose greater than 3 mg is not medically necessary.

Most health plans recognize circadian sleep disorders as true syndromes and treatment is a covered benefit. However, for approval of coverage, case managers should check for the following:

• The patient must be working with a sleep medicine specialist who has ruled out other causes, including the more common sleep apnea, as well as chronic pain and stress.
• After ruling out sleep apnea, the specialist should also consider other issues preventing sleep, including insomnia, chronic pain, stress or fundamental sleep disorders using a polysomnogram or multiple sleep latency tests.

In the case of the 23 year-old man, the physician ruled out common sleep disorders and found the patient’s melatonin levels quite low at the normal sleep times, indicating a delayed sleep phase syndrome. The patient took two weeks off from work to get light therapy treatment. During that time, the treatment worked the patient back about an hour a day until he started going to sleep at normal hours, allowing the patient to return to work on time each day.

References:

• Rimmer DW, et al. Dynamic Resetting of the Human Circadian Pacemaker by Intermittent Bright Light. American Journal Physiology Regulatory Integrative Comparative Physiology 2000; 279:1574-1579.
• Watanbe T, et al. Effects of Phototherapy in Patients with Delayed Sleep Phase Syndrome. Psychiatry and Clinical Neurosciences. 1999; 53:231-233.
• Terman M, et al. Light Treatment for Sleep Disorders: Consensus Report: V Sleep Phase and Duration Disturbance. Journal of Biological Rhythms. 1995; 10:135-147.
• Morgenthaler TI, et al. An American Academy of Sleep Medicine Review. Consensus Statement. Practice Parameters for the Clinical Evaluation and Treatment of Circadian Rhythm Disorders. Sleep 2007; 30:1445-1459.
• Sack RL, e al. Circadian Rhythm Sleep Disorders: Part I, Basic Principles, Shift Work and Jet Lag Disorders. Sleep 2007; 30:1460-1483.
• Sack RL, et al. Circadian Rhythm Sleep Disorders: Part II: Delayed Sleep Phase Disorder, Free-Running Disorder, and Irregular Sleep-Wake Rhythm. Sleep. 2007; 30:1484-1501.