What is a sleep diary?
A sleep diary is a prospective measure that allows people to track their nightly sleep routine. Carney et al. (2012) developed the Consensus Sleep Diary, which is the gold standard measure for sleep tracking.
The sleep diary can be found here.
Each morning, the patient is asked to spend a couple minutes writing down sleep variables from the night before – for example, when they went to bed, when they got out of bed, and how long it took to fall asleep. Typically, patients complete two weeks’ worth of sleep diary to get a reliable and valid index of their sleep pattern.
Information from sleep diaries give CBT insomnia clinicians a good sense of what recommendations to provide to their patients to best improve their sleep. In this article, I provide a general overview of important terms of a sleep diary, ranges of these sleep indices for good sleepers (and poor sleepers), and strategies to improve a patient’s sleep to a normal range.
Important terms to know
Into Bed: Into Bed is the time a patient goes to bed.
Sleep Attempt: Sleep Attempt is the time that the patient tries to initiate sleep. This can be the same time as Into Bed if the person immediately tries to sleep the moment they go to bed. However, some people like to read in bed or do meditation before trying to sleep. In this case, Sleep Attempt begins at a later time compared to Into Bed.
Sleep onset latency (SOL): SOL is the time that people take to fall asleep after Sleep Attempt.
Numbers of awakenings (NWAK): NWAK is the number of awakenings the person has throughout the night.
Wake after sleep onset (WASO): WASO is the total amount of time a person spends awake in the middle of the night. For example, a person could wake up twice in the night, each awakening being 20 minutes each. In this case, NWAK is 2 and WASO would be 40 minutes total.
Terminal wake after sleep onset (Term WASO): Term WASO is the amount lingering in bed after the person wakes up for the last time. For example, if the person wakes up at 7:00am and then spends until 8:00am browsing their phone before getting up, Term WASO would be 1 hour.
Total Sleep Time (TST): TST is the total amount of time a person spends sleeping throughout the night.
Total Wake Time (TWT): TWT is the total amount of time a person spends awake throughout the night.
Time in Bed (TIB): TIB is TWT + TST.
Sleep Efficiency (SE): SE is the proportion of time a person spends sleeping compared to the amount of time they spend in bed (TST / TIB). SE is usually expressed as a percentage; for example, a 50% SE means that a person is asleep only half the time they are in bed.
Bed/Rise Time Variability: These terms refer to how variable a person gets into bed and gets out of bed throughout the week. Less variability means that a person tends to go to bed/get out of bed at a consistent time every day.
Normative ranges on the Sleep Diary
There are general clinical cut-offs insomnia CBT clinicians use to determine whether sleep is closer to the healthy sleeper ranger or the insomnia range.
Good sleepers typically have:
- A sleep efficiency of 85-90% (too low is insomnia range; too high is excessively sleepy)
- A sleep onset latency of 10-30 minutes on average
- A wake after sleep onset of less than 30 minutes
- Bed and rise time variability of less than 1 hour on average
- *The specific number of sleep hours and preference for bedtime/risetime is unique to the person
Evidence-based strategies to improve sleep
As we see from the good sleeper ranges, people with insomnia typically have a sleep efficiency that is significantly below 85 percent. They may also experience difficulties with falling asleep, staying asleep, and/or waking up too early.
There are certain strategies that CBT insomnia clinicians used to break the causes of insomnia.
To put more pressure on the person’s desire to sleep, a sleep restriction protocol can be used. This is typically done by reducing the amount of time a person spends in bed to become more commensurate with how much sleep they are actually producing. For example, if a person is sleeping 7 hours but spending 10 hours in bed, we would ask the person to spend only 7 and a half hours in bed (TST + 30 minutes). A caveat is that we typically do not go below 6 hours for our time in bed prescription.
On the other hand, for people who are excessively sleepy (sleep efficiency > 90%), then we would do a sleep extension and add 15 minutes to the amount of time they are spending in bed.
To regulate our circadian (internal) clock, we typically ask the patient to set an earliest bedtime and latest rise time. For example, setting an alarm for 7:00am every day and getting up at that time.
Finally, to restore an association between the bed and sleeping, we engage in principles of stimulus control. Generally speaking, this means only going to bed when sleepy and getting out of bed if sleep is not coming to do something pleasant instead (e.g., reading a book). More information on stimulus control can be found here.
I hope this post was helpful as a general primer into reading sleep diaries!