Late sleepers may have more than 24 hours in a day

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Most of us love a good Sunday sleep-in. But for some people, getting out of bed each morning can be a constant battle that significantly disrupts their lives.

Now, researchers from Flinders University are a step closer to discovering what keeps these late sleepers up at night and consequently reaching for the snooze button the next day.

Led by renowned sleep specialist Professor Leon Lack, the team is about to begin the second phase of a three-year study investigating the role of the body clock in delayed sleep phase disorder, which is characterised by a persistent inability to fall asleep and wake at a conventional time.

Professor Lack, who heads Flinders Sleep Research Laboratory, said initial results showed that the circadian rhythms, or internal body clocks, of individuals with delayed sleep phase disorder ran slower than usual, thereby making it difficult for them to go to bed and wake up early.

“Late sleepers can’t get to sleep until 2am or 3am at the earliest, or in some cases as late as 4am, which makes it very hard for them to get up for their commitments the next day,” Professor Lack said.

“We’ve been investigating what causes people to be late sleepers and one of the most plausible explanations we’re perusing is that their body clocks run longer than 24 hours,” he said.

“Most people have a 24-hour body clock, it’s a natural rhythm that influences sleepiness and core body temperature but for people with delayed sleep phase disorder it takes longer to complete the cycle so they tend to go to bed later and wake up later.”

Professor Lack said preliminary results showed a slower body clock was the probable cause of delayed sleep disorder, however wider tests with a larger population would now need to be conducted to confirm the findings.

“If we establish what we’re expecting to find it will reinforce therapies that we know can help, such as bright light therapy to induce alertness in the mornings and melatonin to encourage earlier evening sleepiness.

“Exposing people to a bright light as early in the day as possible informs the body clock that it should be awake so therefore they fall asleep and wake up earlier on subsequent nights.”

With a large percentage of the population suffering delayed sleep phase disorder, Professor Lack said it was imperative to find a cause of the condition.

“As many as 10-15 per cent of adolescents and young adults have this problem and it can become quite disruptive in their day-to-day lives.

“It causes young people to be late for school and when they do get to school they’re inattentive until their body clock finally wakes up. Adults can also have trouble holding down jobs because they’re always running late for work so it does have a detrimental effect on lives.”

For more information or to take part in the study, call 8201 2349.

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6 thoughts on “Late sleepers may have more than 24 hours in a day

  1. I have this problem, and it’s affects my life so much! I am so weak in the morning that I fear one morning I won’t be able to hop out of my bed ever again and be stuck in my bed for the rest of my life, and I in the healthy weight range. Because I’m tired for most of the time when I am awake I have poor brain functioning and so my decision-making and mental alertness is impaired a great deal. I have tried to go to bed at earlier times, but my body is just not willing to sleep until 2-3 AM, and so I would have wasted my time laying there. I have been yelled at by close friends, family and employers for being tired, and sleeping in, but they don’t understand that I have a lot less control over the situation as they think I do. I don’t want to sleep in; I’m just physically too weak to get up. I have even gone to the gym to see if strengthening my body and my legs especially, to see if that made it easier to get me out of bed and it hasn’t made it any easier to get out of bed.

    I am going to give light therapy a go. I’m not going to like how people will have the ability to be able to look in my bedroom window but I guess many solutions come with consequences.

  2. I myself is a 23 years old undergrad at FU studying Environmental Management and I am a late sleeper. I find it hard for me to sleep most of the night and my regular bed time is 3-5 A.M during the past holiday break. It has been a bad habit of mine for years and I find it very hard to cope with my regular study time resulting in me not being able to attend my class or sometime even fail my topics. I would like to receive more information on this study and take part in this research to help understand the nature of this late sleep habit. Please email me at or contact me on my mobile 0431 434 543.

    Sid Binchai

  3. Is it really a disorder?

    because I was going to bed between 3am and 4am everyday for around 10 years…

    I would sleep in till 2pm each day….

    it was not a disorder, but a choice. I changed this habit about 12 months ago and I am in bed by midnight 70% of the time. The other 30% of the time I get to bed by 1am…

    I choose to stay up, because I function better as it gets later. I would rather be up late, rather than getting up early…

    I don’t know why I changed this habit, maybe its because of other commitments, and also insufficient time. There are things which I have to do during the day, which leaves me no choice but to change my habit, so I can get things done during the day…

    but saying that, I love staying up. I am a night person and enjoy late nights…

    people may wonder why I don’t go to sleep the same time as the majority of people, but I wonder why people are sleeping so early, besides having to be in bed by a certain time, because of work commitments etc etc…

    even if I woke earlier, I would still rather stay up at night…. To me it feels like there is not enough hours in a day and night… I feel though I need more time, that’s why I stay up.

    your able to just keep doing things, for example, researching, working, reading, gaming etc etc..

    I am certainly not a morning person, and am not happy waking up early, even though I like the sunrise and beautiful sunny morning, I don’t feel the same as I would if I woke up around late morning.

    so it was not a disorder as such, but a habit and the love of late nights.

    but I can easily change the habit to my dislike…

  4. This is very much “really a disorder”. When somebody has a period in his or her life in which the person’s natural sleep/wake schedule shifts later and eventually self-corrects (which is actually common during and after adolescence), or when somebody stays up late and sleeps late out of preference, neither by any means makes circadian rhythm disorders any less real. What comments asking if this is “really a disorder” do, however, is to minimize very real, very debilitating conditions.

    I am one of a handful of sighted [non-blind] people I know of who has non-24 sleep-wake syndrome (a CRD), and I’m the ONLY one of them who still manages to have a career, which I’ve done at significant expense to my health when I’ve held positions that required me to be in an office during “normal” business hours. The only reason I’m still able to remain employed is because I work for a company that allows me to work primarily from home, and I do a lot of things to try to “control” my sleep schedule; i.e., light therapy, dark therapy (when possible) and keeping as closely to a 28-hour day as I can, since it gives me a predictable schedule, albeit one that slides across 24 time zones in 7 days.

    The key differentiator between a very-real circadian rhythm disorder and a “bad habit” is that habits can be changed with effort and discipline. CRDs cannot.

    When I worked 9-5 jobs, I fell asleep later and later each night and functioned on less and less sleep each day- despite multiple sleep-inducing medications, impeccable “sleep hygiene”, etc. By each weekend, I was exhausted and ended up sleeping most of the weekend, returning to work on each Monday more exhausted than the week before (you can’t make up for lost sleep). I always cycled quickly through early sleep cycles; i.e., at times when my natural bedtime was at a socially-acceptable time and afforded me 7-8 hours of sleep before I had to get up for work, that natural sleep time would shift later and later quickly over each day. When I was in cycles where I was falling asleep at 5:00 AM and having to get up at 7:00 AM, the progression of my natural sleep time was much slower.

    Eventually with each job that required me to work 9-5 week after week, I’d end up sick because my immune system was shot. The longest I ever held down a job on that schedule was two years, and only then because I was able to negotiate some later work hours at times and took chunks of time off. My health suffered immensely. I’ve been with my current employer for the better part of a decade because of the flexibility it offers in terms of scheduling, and I perform well because my immune system is no longer shot and I’m generally able to get adequate amounts of sleep, albeit at highly-unusual times most days.

    Let me make this very clear: given the choice, I would “rather” fall asleep before 10:00 PM every night and wake up by 6:00 AM every day- in fact, I’d even prefer earlier times for both. Society rewards “early birds” who are in the office by 7:00 AM. Public transportation and highways are less crowded if you’re going to work two hours earlier than most people. Utilities cost less if you’re asleep near dark and awake near dawn. Nobody thinks you’re “lazy” or “unmotivated” if you’re “early to rise and early to bed”.

    Moreover, I actually prefer daylight and would much rather be awake every day during daylight hours- I wouldn’t have to worry about making noise and waking up my neighbors because I’m getting up at 11:00 PM to start my day or because I really need to do the dishes (and wish I could vacuum) at 3:00 AM. I wouldn’t have to worry about whether I’m able to order delivery food because they close long before I’m going to be awake. I wouldn’t have to be waken up multiple times during my sleep because a package is being delivered or a meter reader needs access to the utility meters, or any other reason why my phone or doorbell rings.

    No sane person would want to have an ever-shifting sleep schedule, or even “just” a sleep schedule that means they’re involuntarily awake until very late at night and exhausted every day because they’ve had to get up at a time when their bodies are supposed to be deeply asleep.

    So if you wonder if this is “really a disorder”, consider this: suppose you were told that starting tomorrow, you would have to get up for work at 1:00 AM and would therefore have to go to bed at 5:00 PM. Imagine doing that for the rest of your life. Now imagine that instead of having to go to bed at 5:00 PM and get up at 1:00 AM, you had to go to bed an hour earlier every night and get up an hour earlier every day. That’s my world, and it is very, very REAL.

  5. I just wonder if it has to do with the amount of stimulation our brains receive these days from computers, TVs and other screens around us, as well as all the caffeine and sugar we consume, and extra responsibilities we all have thesedays (as well as stress and worry). It probably takes a lot longer these days for people to wind down for sleep, especially if they don’t know how to (eg. trying out things like meditation, massage, soft music, bath, warm drink, wheatbags, herbal remedies, gentle exercise, etc.) I don’t like mornings myself, and certainly work better in the afternoon and night time, but the more research that goes into this topic, the better, because the more tired people are in the daytime, the more grumpy and unfocussed they are, which doesn’t help anyone! Perhaps if people tried out ‘screen free’ days away from Facebook, email, etc. it may make a difference to their sleeping patterns. Although I think we go through different stages in our life. I know that in school I would avoid doing homework when I got home from school, to give my brain a break, and then wake up really early in the morning to do it before leaving for school and that seemed to work for me at the time. These days, being a parent, I savour sleep far too much to do something like that now!

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