When we are in the lighter stages of sleep it is possible to be asleep without realising it. We know that both good and bad sleepers can find it difficult to be sure if they have truly been sleeping, or how long they have spent awake during the night.
Research has shown that people with poor sleep tend to overestimate how long it takes them to fall asleep. This can be demonstrated when they are brought into the sleep laboratory when the precise time it takes them to fall asleep (sleep latency) can be determined by polysomnography recording.
People with normal sleep can also make these errors when estimating their sleep.
This may be due to a combination of reasons such as:
• The stage of sleep they are woken from
• How many times they have woken up in the night
• Lifestyle factors, such as stress and alcohol consumption
We know that sleep does not occur in one continuous block, but rather that we move in and out of different sleep stages, often when we transit from one sleep stage to the other. It is normal to briefly wake during the night but then return to sleep quickly. Many people are however unaware of this fact, and this can lead to unreasonable expectations of their sleep.
If people appear to have objectively normal sleep but still perceive their sleep as abnormal then we call this sleep misperception. This is also a problem but one which needs a different approach to insomnia. In the case of sleep misperception, we focus on explaining what normal sleep physiology consists of and also reassure the patient that the amount of sleep that they are getting is normal.
It may also be that daytime symptoms, attributed to a perception of a broken night, are actually due to some other problem that needs to be separately explored. Sleep diaries can be super helpful to spot what’s going on and share with a professional for an appropriate course of action.