Sleep Inertia is a physiological state characterized by a decline in motor dexterity and a feeling of grogginess when a person is abruptly awakened.This impaired alertness may interfere with the abilities of the person to perform mental or physical tasks. The capability of the person to react to a situation will be weakened. Thus increasing the possibility of the occurrence of critical errors2
Causes of Sleep Inertia
The causes of sleep inertia can be listed as follows
1.Sudden awakening of sleep is the main cause of sleep inertia and its effect will last about 30 minutes.
2.Sleep deprivation also poses increased causes of sleep inertia.
3.The effect of sleep inertia is low when a person is awakened from deep or slow wave sleep.
4.Sleep inertia is extreme when the awakening occurs at the trough of the core body temperature3
Effects of Sleep Inertia
Sleep Inertia is a normal part of the life but it becomes severe during certain situations, where the effect of that would be disastrous.
The major effects of sleep Inertia are
1.Decrease in the mental ability of the person.
2.Impaired capability of the person to make decisions
3.It reduces the performance of the person and his response time on tasks3
Sleep Inertia affecting Pilots:Major cause of the Air India Express flight 812 crash
Sleep Inertia tends to be a cause for the impaired performance of the pilots during long haul flights. The pilot when awakened suddenly during a deep sleep experiences sleep inertia which may impair his whole mental and physical activities, which leads to a disastrous outcome. This was the case in the fatal crash of the Air India Express Boeing 737-800 flight. The flight which was en-route to Mangalore from Dubai crashed by over shooting the runway on 22 May 20101
Cause of the accident
The Captain of the flight was Zlatko Glusica and he was assisted by co-pilot A.S.Ahluwalia. The captain of the flight was asleep for most of the flight which is evident from the voice recorded in the cockpit voice recorder and then made critical errors before landing which led to the fatal crash4 The captain was woken shortly before descent which he was to fly. The pilot was disoriented after being waken up and his overbearing character also added up as he ignored the co-pilots call to abort the landing and his suggestion to have a go around. The captain misjudged the length of the runway and touched down 1600m beyond the threshold, and overran the end of the runway crashing down the steep slope. About 158 people were killed including the crew and there were only 8 survivors1
From the above report it can be concluded that the sleep inertia affected the pilot's timely response to the situation. The pilot had a groggy feeling as he was abruptly awakened. Hence adequate sleep is required for a pilot to avoid sleep inertia and its adverse effects.
Want to know more?
- Science direct - Sleep medicine reviews
- This page provides various articles related to sleep inertia and its effects.