WOULD YOU DESCRIBE YOURSELF as “an early bird” (i.e., an early riser) or as “not a morning person” (i.e., a late riser)? Although early risers and late risers appear to be opposites, they share a characteristic: both have a natural circadian rhythm that is out of sync with the societal norms for sleep and wake times.
The circadian rhythm, commonly called the “biological clock,” refers to the rhythmic change in physiological activities such as sleep and wake that occurs on a daily basis. In early risers, the sleep/wake phases naturally occur two to three hours earlier than normal. They awaken early in the morning (e.g., 5:00–6:00 am) and are ready to go to bed by early evening (e.g., 9:00 pm).
In late risers, the sleep/wake phases naturally occur two to three hours later than normal. They awaken late in the morning (e.g., 10:00 am) and are ready to go to bed in the early hours of the morning (e.g., 1:00–3:00 am).
People with naturally early sleep/ wake phases have the sleep disorder “advanced sleep phase syndrome” (“ASPS”), and people with naturally late sleep/wake phases have the sleep disorder “delayed sleep phase syndrome” (“DSPS”).
When trying to go to sleep or awaken at a “normal time,” people with ASPS or DSPS will struggle with sleepiness and insomnia (i.e., inability to fall asleep at a desired time or inability to remain asleep during a sleep period).
People with ASPS are sleepy in the early evening because their body biologically is ready for sleep, whereas people with DSPS have daytime sleepiness because they wake up soon after going to sleep and their body biologically still wants to sleep.
People with ASPS may believe they have insomnia because they awaken early, and people with DSPS may believe they have insomnia because they cannot go to sleep at an earlier time. When people with ASPS or DSPS are allowed to sleep at will (e.g., during vacations), struggles with sleepiness and insomnia are resolved because they are following their natural circadian rhythm.
However, sleep/wake phases in people with ASPS or DSPS can be shifted so that they take place at socially normal times. This shift may be accomplished with bright light therapy, melatonin treatment, or chronotherapy. Bright light therapy involves exposure to strong-intensity light soon before going to sleep (for ASPS) or on awakening (for DSPS) to shift the sleep/wake phases to a later or earlier time, respectively. Melatonin, which promotes the onset of sleep, is taken at certain times of a person’s sleep/wake cycle to aid the onset of sleep at a desired time. Chronotherapy involves progressively advancing or delaying sleep or wake times (for ASPS or DSPS, respectively) until the desired sleep and wake times are achieved.
For some people, being naturally an early or late riser does not cause substantial problems with sleepiness and/or insomnia. However, if you are consistently an early or late riser and sleepiness and/or insomnia are problematic, you may have ASPS or DSPS. A visit to a sleep disorders center is necessary to rule out whether you have ASPS or DSPS or whether you have another problem such as depression or another sleep disorder that can contribute to symptoms of daytime sleepiness, insomnia, and early or late sleep/wake phases. Regina Patrick, RPSGT, RST, is a freelance writer/editor and is a registered sleep technologist. She has been involved in the sleep field for more than 30 years. ✲
