Surely the reader has ever thought of the phrase “I can’t get up today” just as the alarm clock starts ringingas the song by Mecano, the mythical Spanish pop group of the 80s, said. But the alarm clock It is one of those machines that we have inevitably gotten used to obeying.
And yes, we got up, but for a while we are sleepy, disorienteds and our cognitive performance, let’s say, is quite diminished. He already said it physiologist Nathaniel Kleitman in 1939: You are not at your best when you just got up, no matter what time it is.
This common phenomenon is known in the scientific literature as sleep inertiaand it has come to be considered a third process in sleep regulation.
The circadian and homeostatic process
The two processes that have traditionally been in charge of regulating when we will have a greater probability of sleeping are circadian and homeostatic. The first would be like a clock of needles that marks the most appropriate time to start the break; and the second, one kind of hourglass (or the compound called adenosine) that measures how many hours we’ve been awake.
So that our dream appears without difficulty, both processes must engage in a kind of coordinated dance, in such a way that the most appropriate time to sleep also coincides with the moment in which the adenosine accumulated during wakefulness is optimal.
Well, there are those who have considered sleep inertia as a third process in this regulation. I would act right after waking up in the morningcounteracting the low probability of sleep that would mark the homeostatic process and the high probability of wakefulness that would indicate the circadian process.
What happens in that half hour after we wake up
Although the process of waking up has been studied less than that of falling asleep, the truth is that some data on neural activity show that the brain remains in a state more similar to sleep when we just opened the eye than before we started to sleep. Furthermore, it is also known that cerebral blood flow is slower in the transition from sleep to wakefulness than just before surrendering to the arms of Morpheus.
So there seems to be a physiological basis for our having a hard time getting going every morning. And evolutionarily, would it have any advantage? We might think that, in nature, if something wakes us up, it would probably be better to be up and running in a matter of split seconds. However, given the complexity of the neural mechanisms involved in the transition between sleep and wakefulness, one hypothesis is that sleep inertia would be a way to protect this process by avoiding abrupt transitions.
On the other hand, this inertia means that when we wake up at night, it is usually easy to go back to sleep. Another hypothesis about the usefulness of gradual awakening would be avoid intrusions of dreams into wakefulnessin the form of hallucinations, in case of waking up in the middle of the REM phase.
Factors influencing trance
Although it is considered normal, there are factors that can contribute to increasing this trance. For example, not getting enough sleep at night and waking up earlier than our body needs will increase sleep inertia. The same happens if we drag a chronic sleep deficit.
The time of day or night in which the awakening occurs also influences: the inertia of sleep is greater when we wake up during our biological night, when the organism understands that it is still time to be sleeping. And does the phase of sleep in which we find ourselves influence? In this case there is some controversy: it is not clear if the inertia is greater when awakening in deeper phases or not.
How does sleep inertia affect us and how can we reduce it?
This failure to boot has an impact on different aspects of the cognitive performancebut at what levels? On the one hand, there are studies that have only found effects on reaction speed. Others also indicate that the precision would be diminished.
In any case, the execution of complex tasks that require greater attention would be the most affected by sleep inertia. Therefore, it would be advisable to carry out activities that require memory, calculation, decision-making or psychomotor coordination after those first 30 minutes of wakefulness.
As shown, a retrospective analysis of more than 400 US Air Force accidents revealed that accidents associated with human error were most frequent in the first hour after awakening. As the reader surely intuits, sleep inertia can pose a problem in the performance of emergency service workers such as medical personnel or firefighters.
What can we do so that it does not affect us so much?
Although sometimes it is unavoidable, there are things we can do to make it less difficult for us to wake up. On the one hand, we know that little sleep makes inertia greater. We also know that if we wake up during our biological night, it will also take longer to start. Therefore, getting enough sleep every night and doing it at the right times can reduce this inertia. And if what we want is to reduce the inertia of the nap, the shorter it is (always less than 30 minutes), the less it will cost us to recover our performance.
In the case of on-call staff, although bright light upon awakening would increase subjective alertness, no beneficial effect on objectively assessed performance has been found. It seems that sound and music could be effective in reducing sleep inertia.
Based on what we know about thermoregulation and sleep, cooling the extremities could also wake us up, although it has not been proven at the moment. And while physical exercise upon waking does seem to increase alertness, it hasn’t been shown to improve performance afterwards either. Caffeine could work if we take it before a nap, but it is not recommended.
Summarizing: to reduce the consequences of sleep inertia on a day-to-day basis, try to get enough sleep every night. And if they have to carry out a complex and important task, it should not be the first thing they do after the alarm goes off.