65. Sleep inertia

18 March 2012 at 06:54 | Posted in Circadian rhythm | 8 Comments
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Sleep inertia refers to temporary cognitive problems, low levels of alertness and vigilance, and impaired motor dexterity immediately upon awakening from an episode of sleep.  The ability to perform mental and/or physical tasks including learning is deficient for a period of time.  Executive functioning may be especially impaired; decision-making can be impaired by 50%.  Sleep inertia has been shown to be a robust, quantifiable process.

That’s the fancy way of saying that one feels groggy, slow, disoriented and a bit stupid for a while after getting up.

Normal people experience sleep inertia on abrupt awakening from a nap of more than 30 minutes and on abrupt awakening in the middle of the night.  It may last from 5 minutes to an hour or more.  The stage of sleep may be of some importance for the degree of impairment and how long it lasts.   Some degree of sleep inertia is possible even when the sleep from which a person has awoken may have fully dissipated their sleep need

“Circadian misalignment is the basis for all circadian rhythm sleep disorders. These disorders are often associated with impairments of cognitive performance that can have adverse effects on school and work performance, overall quality of life, and safety.”  [Reid et al]  Sleep inertia is common in circadian rhythm disorders and it seems to be more severe and long-lasting here than in normal people.  On top of this, people going to work or school by 9 a.m. are getting up in the middle of their biological night where sleep inertia has been shown to be 3.6 times worse than in “daytime”.

A few recent quotes from people in our support group

show that we find sleep inertia to be a major problem:

–The people I was traveling with even thought I was dead on one occasion because of my usual “coma” type sleep/difficulty waking.

–My son does that comatose thing when he is sleeping too.  NOTHING will wake him.  SO the sleep doc’s office calls and says to be sure and wake him on schedule.  I just said “Huh? That’s supposed to be funny, isn’t it?”

–I have the very deep sleep characteristic as well…  I’ve slept through fire alarms, even a jackhammer tearing up the street literally right outside my window.  […]  I’ll also apparently have limited conversations with people while still asleep, though I’ll have no recollection.  My college roommate told me I would crawl halfway down the ladder from my bunk and turn off my alarm clock with my foot, still dead asleep.

–Of course it doesn’t help that I won’t be anywhere close to alert for at least an hour after waking up if it’s morning…

–No one could understand how I could always be late for work; my bosses said “please just call and let us know if u will be late.”. What the?  There was never any recollection of turning off multiple alarms (if I did–maybe they ran out–I could never figure it out).  How could I call in my sleep? ;).  No options, if you are deaf, you can’t hear, and it’s like I was deaf or in a coma.

–I too have slept through fire alarms, normal alarms, building work in my room at one point etc.  My parents always said I could sleep through a nuclear blast 😛  And I also talk in my sleep when someone’s trying to wake me up — not much though, just enough to reply “yes, I’m getting up” or something similar.

–The last time I was working regularly I had to budget at least an hour to get dressed because I could count on “losing” about 30 minutes every morning.  Just standing in the middle of the kitchen or in the shower asleep.

–Similarly, I set an alarm for three hours before class starts (takes 10-20 minutes to walk to class) because I seriously lose time when I wake up, especially if I wake up after fewer than an optimal number of hours of sleep. I don’t know if I sleep standing or not, but I definitely haze out and lose time.

–My boss can’t understand my DSPS.  And now I have an accommodation so I can work noon to 8:30 pm and still I don’t hear the alarms and often wake up half an hour before I need to be at work, thus I am often (OK, almost always) a little bit late even at noon.  I was told at work that since my supervisor was going to be on vacation, I’d need to come in to work at 8am for that week.  (I have a medical disability accommodation).  I explained it to them like this….if I was in a wheelchair, and my boss normally did something like climbing a ladder to replace lightbulbs, would you expect me to figure out a way to do that in her absence?  Would you remove a wheelchair ramp for a week for someone and expect them to crawl up a few steps for a week?

–I do wanna point out, my partner is the least DSPS person I know, he’s very average, sleeps 8 hours if allowed, but does very well on 6, works full time 9-5 without a problem. My point is, he’s normal 😛  And if you set an alarm for his middle of the night, he will also be comatose-like and a total zombie even if he does manage to hear it and get up. And he’s actually fallen asleep in the shower/kitchen while getting ready for work before, when he’s had to get up at hours like 3-4am (which is very rare). So I don’t think that this type of sleep is DSPS or N24 specific .


 Bruck D, Pisani DL.  The effects of sleep inertia on decision‐making performance.  Journal  of Sleep Research.  1999; 8: 95–103.

Matchock RL.  Circadian and sleep episode duration influences on cognitive performance following the process of awakening.  International Review of Neurobiology. 2010;93:129-51.

Achermann P, Werth E, Dijk DJ, Borbely AA.  Time course of sleep inertia after nighttime and daytime sleep episodes.  Archives italiennes de biologie. 1995 Dec;134(1):109-19.

Groeger JA, Lo JC, Burns CG, Dijk DJ.  Effects of sleep inertia after daytime naps vary with executive load and time of day.  Behavioral Neuroscience.  2011 Apr;125(2):252-60.

Reid KJ, McGee-Koch LL, Zee PC.  Cognition in circadian rhythm sleep disorders.  Progress in Brain Research. 2011;190:3-20.

Scheer FA, Shea TJ, Hilton MF, Shea SA.  An endogenous circadian rhythm in sleep inertia results in greatest cognitive impairment upon awakening during the biological night.  Journal of Biological Rhythms.  2008 Aug;23(4):353-61.


66.  Next post:  67.  Blogathon:  “Dear Diagnosis”



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  1. I go to the medic, and he recommended Agomelatine, what you think about this medicament? i see very bad contraindications.

  2. Sorry, I don’t know anything about Agomelatine, other than what I can read on Wikipedia. It appears to be primarily for severe depression with some effect on circadian rhythms. Best wishes.

  3. What i wonder, is, if DSPS is supposed to runs in families, if any DSPS person has children, what are the chances of the child having it too? I wish someone would figure out this angle of DSPS. What if two DSPSes get married and have children lol? Would their kids have N24? It seems like something to consider lol.

  4. I’m of two minds about your “sleep like the DEAD” reports:

    1- so sorry you’re dealing with it too, and
    2- I’m so glad to hear I’m not the ONLY one on planet earth who can sleep through anything and everything. I simply do NOT wake to sound.

    “JetLagged for Life” on ADDandSoMuchMore.com tells of some of the things I have slept through, so I won’t add to your examples here. Just wanted to ring in to say I FEEL YOUR PAIN!

    LOVE your blog – working my way through it.

    Madelyn Griffith-Haynie, CMC, SCAC, MCC
    – ADD Coach Training Field founder; ADD Coaching co-founder –
    (blogs: ADDandSoMuchMore, ADDerWorld & ethosconsultancynz – dot com)
    “It takes a village to educate a world!”

  5. Hi. Thanks for the nice words. This blog-post was written while I worked full-time. Now retired, I sleep as much as I like whenever I like. It’s very irregular, but I’m no longer sleep-deprived. And, much to my own surprise, I can wake up to just one alarm clock — which I do about twice a month! Off to read “JetLagged for Life” now.

  6. Retired! I will probably need to work until I die, but I have no choice but to sleep as long as my body wants. Once it lets me fall asleep, I’m down for the count! Since I live alone and don’t wake to sound, it makes for an interesting schedule -but I’m rarely sleep deprived!!

  7. Didn’t see a number for “comments left” but if over 90,000 hits is any indication, there may be enough of us to pitch a study to someone [preferably with an academic interest and skill in getting a research grant] and 23andme.xxx for a genetic study to see what all of us have and do not have in common with the “18” clock genes. I’ve had this all my life and marked it up to being a shaken toddler survivor. After a fall in ’91 the 9-5 as a technical writer became impossible. My wife/caretaker now has Parkinson’s. The pertinence or impertinence of it is that the Michal J. Fox Foundation paid for my wife’s membership in 23andme for a full genetic workup and periodic questionnaires about symptoms and such. The sooner this sort of thing could be set up for us, the sooner someone will have a bottom line of medical and worker productivity losses to take to the Institutes of Health and say “this is a significant health [and national security] issue [my favorite current attention getter phrase?]] I spent four years in the US Navy and had to fight this second war every second I was on watch. I hope one of you gets a “good morning, you have a new comment message when I post this.

  8. Hello L P Luigi Espenlaub,
    You are exactly number 400! (I just looked up how many comments have been approved.)
    Also looked up the Fox Foundation. Now there’s a non-profit with a lot of money. Will be nice when we get there! Yes, we have a non-profit, just a couple years old with members in several countries.
    It is at: http://www.circadiansleepdisorders.org/ You may join!
    The non-profit was started by some members of the niteowl mail list; see
    On the list we have people with DSPD and people with Non-24. Please do join us. We are at least 200 more-or-less active members and there seldom goes a day with no messages. Its purpose is to be a support group and we often talk about how to work for greater awareness among doctors and the general public. I do like your suggestion to “pitch a study to someone” to get us studied! Most circadian rhythm research has been done on normal sleepers, usually male and college-age. We are more diverse than that. And we can’t know if results from studies of normal sleepers also apply to us.
    I hope we’ll hear from you on the list!

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