What are CRSD (circadian rhythm sleep disorders)?
Circadian in Latin means “approximately” (circa) “a day” (diem). Circadian rhythm is the name given to your 24 – hour internal rhythm which controls your sleep – wake cycle. Your internal rhythm is actually 24 hours and 11 minutes, but light will set your internal clock to the external light – dark cycle (24 hours). (link to learn about your sleep, circadian rhythm)
CSRD are a group of disorders caused by a misalignment between the body’s internal sleep – wake cycle and the external light – dark cycle. This can happen due to an altered phase (internal) or work schedule/ travel (external).
Advanced sleep wake phase disorder (ASWPD)
I wake up very early (3-4am) and feel ‘fresh’ in the morning hours. I feel tired in the evening starting 5pm, and have difficulty with evening chores like cooking dinner and helping children with homework. I can fall asleep by 7pm. Even if I stay up late, I still wake up by 4am.
You probably have ASWPD, which is caused by an advance in your internal clock phase in relation to your desired sleep-wake times.
People with ASWPD fall asleep (6–9pm) and wake up (2-5am) very early. They describe feeling very tired in the evening, leading to difficulty with their evening chores and activities like parties, marriages, school functions and dinner meetings. Even if they manage to delay their bedtime, they still wake up between 2-5am, and will feel sleepy during the daytime due to reduced sleep time.
Delayed sleep wake phase disorder (DSWPD)
I have difficulty waking up in the morning and am frequently late for my 8am class. I am sleepy during the daytime and fall asleep frequently, especially during my morning classes. Although I am sleepy all day, I get a ‘second wind’ between 8-9pm and feel great during this time. I have difficulty falling asleep till 2-3am. During weekends and holidays, I am able to sleep till 2-3pm, unless someone wakes me up.
You probably have DSWPD, which is caused by a delay your internal clock phase in relation your desired sleep-wake times. People with DSWPD fall asleep (2-4am) and wake up (10am to noon) very late. They may feel sleepy all day, due to not sleeping enough, but become energetic in the evening and night starting 6-9pm.
Due to difficulty waking up, they are frequently late for morning classes and work. DSWPD teenagers are frequently told by their parents, “go to sleep on time so that you are not late for classes”.
Non 24 -hour sleep wake rhythm disorder is characterized by delay in sleep time by 1-2 hours every day. This is seen mostly in blind individuals since their clock cannot be set by the light-dark cycle, but is also seen rarely in sighted individuals.
Jet lag is seen in association with travel involving rapid time zone changes. Due to rapid changes in the time zone, you may find yourself trying to sleep and wake up at the wrong circadian time.
Shift-work sleep disorder is seen in rotational shift workers (especially when they work night shifts). Shift work is associated with difficulty sleeping and sleepiness during work. This is the result of trying to sleep and stay awake at the wrong circadian time.
How are they treated?
If you are comfortable with your sleep-wake times, treatment is not required. However, if you are having difficulty adjusting with your school work, job or home responsibilities, then treatment is required. Treatment will depend on the specific CRSD.
Goal of treatment is to fit your sleep-wake pattern to match your lifestyle. Treatments include:
1. Bright light therapy to reset your rhythm
2. Sleep habits to feel more relaxed at bedtime.
3. Lifestyle changes: appropriately timed light exposure and exercise, avoiding caffeine and nicotine late in the day.
4. Medication such as melatonin
Understanding your condition and appropriate timing of therapy is important for treatment to be successful. If you feel that you have a CRSD, make an appointment with AMARA Sleep (link to make an appointment) today.