Cortisol Awakening Response (CAR)

What this laboratory test evaluates

Research has found that a lower cortisol response to awakening is often seen in individuals with:
• A high amount of psychosocial burnout
• Chronic fatigue
• PTSD
• Seasonal affective disorder (during winter)
• Nightshift work schedules
• Sleep apnea
• Short sleep cycles
• Chronic inflammation
• Adrenal insufficiency
• Lack of morning sunlight exposure
• Hippocampal damage or atrophy
• Amnesia (due to temporal lobe damage)

Factors associated with an elevated CAR include:
• Ongoing job-related and perceived stress (CAR is significantly higher on work days)
• Immediate access to light upon awakening
• Depression
• Ovulation phase of the menstrual cycle
• Sleep issues
• Older age

Cortisol levels should be at their highest level 30 minutes after waking up in the morning, decreasing gradually over the course of the day, reaching their lowest point at bedtime. The resulting diurnal curve or pattern allows health care providers to pinpoint issues with adrenal gland function. Alterations in this pattern can results in symptoms related to stress, fatigue and insomnia.

Useful for:• Feeling stressed
• Fatigue
• Insomnia
• Nervousness/Irritability
• Salt/Sugar cravings
• Dizzy spells
• Headaches
• Decreased stamina
• Burn out
• Chronic disease
• Anxiety/Depression

Additional test information

The cortisol awakening response is the natural rise in cortisol that is seen 30 to 40 minutes after awakening followed by a noticeable drop by 60 minutes. CAR can be utilized as a biomarker for assessment of the HPA axis function in routine clinical practice. CAR is influenced by overall HPA reactivity, as well as a person’s anticipation of stress.
The CAR involves a measure of the percent rise in cortisol from awakening to 30 minutes post-awakening and the expected decline in cortisol seen at 60 minutes. The Diurnal Cortisol Profile involves 4 cortisol samples taken at 30 minutes post-awakening, noon, dinner time, and bedtime. While the CAR can provide the best information on HPA axis reactivity and function, the Diurnal Cortisol Profile can identify dysregulation in the natural cortisol circadian rhythm.

Collection and processing

• Sample type: Saliva
• Fasting: No
• Estimated laboratory processing: Results should arrive 3 to 5 days after the lab receives samples.

How Sunridge uses laboratory information

Sunridge considers the medical question, symptoms, history, medications, prior results, and whether the finding could change care before recommending testing. A laboratory result is not interpreted in isolation and does not establish a diagnosis by itself.

Before requesting this test

Availability, collection requirements, eligibility, and processing estimates can change. Sunridge reviews each request and, when appropriate, creates the order through Fullscript. Follow the current instructions supplied with the approved order.