Friday, 20 January 2012

Happily dreaming of a slimmer waistline

It's fairly easy to spot someone who hasn't had a great night's sleep. The bleary eyes. The birds-nest hair. Not to mention the  constant growled demands to be left alone unless you come bearing coffee. When we find ourselves in this position it's fairly clear that those eight hours a night are important for our sanity. Very important indeed. So why is it that a lack of sleep can leave us feeling so lacklustre?

The wrong side of bed


You're probably well aware of the fact that sleep is one hell of an important pastime, after all it's intricately involved in such fundamental processes as memory consolidation and wound healing. Yet the first thing we seem to notice when we've missed out on that cathartic coma is the storm clouds brewing inside our heads. Yes a lack of sleep can turn even the most jolly Roger into Oscar the Grouch in no time, and a few short  years ago researchers figured out why.



To do this the scientists conducting the study kept 13 participants awake for 35 straight hours before strapping them into an fMRI and showing them 100 images, which ranged from emotionally neutral to very upsetting. The resultant scans were compared to those obtained from participants who hadn't drawn the short straw, and were thus well rested, and showed that in the sleep deprived brain the disturbing images led to a pronounced activity spike in the centre for emotional reactions, the amygdala. So the distressing images were leading to more negative feelings in the sleep-deprived subjects, or as the researchers put it "without sleep, the brain had reverted back to more primative patterns of activity, in that it was unable to put emotional experiences into context and and produce controlled, appropriate responses". Tracing the patterns of activation back further showed them why. Instead of connecting to the prefrontal cortex, the site of logic and reason, the signals from the amygdala were actually connecting to the ancient emotional accelerator, known as the locus coeruleus. So rather than being rocked back and forth whilst being reassured that the images were just images, the amygdala was instead being pumped full of noradrenaline and ramped up into a veritable frenzy of emotional instability. And haven't we all been there... But just when you thought a bad night's sleep couldn't make you feel any worse, scientists have recently gone ahead and announced that it may also be making you fat.

Dreaming of a slimmer waistline


That's right new research suggests that it's not just your hypothalamus that has it in for your waistline, it's also your bed. Or more importantly what you're doing in it. The study, published in the Journal of Clinical Endocrinology and Metabolism, involved monitoring the neural activation of 12 normal-weight males while viewing images of high and low calorie food, the morning after either a solid 7 hours with the sandman or a "night of total sleep deprivation" (their words not mine). Yep, under strict instructions from Lionel Richie, participants were kept awake All. Night. Long. Watching TV, playing board games with the researchers and perhaps even dancing on the ceiling. All that can be certain is that the participants were running with the night (that's the last one I promise), with one exception. No food. All participants were given a standardised 700kcal dinner before bed on, both their sleep and sleep deprived nights in the lab and nothing else until just before the scans when they were given a glass of curdled milk. The fMRI results showed that a lack of sleep lead to significantly greater neural activation within the right anterior cingulate cortex despite a lack of differences in blood glucose levels. Interestingly higher activation of the anterior cingulate cortex, located within the frontal cortex, has been reported in obese individuals and is thought to be linked to enhanced perceptions of food-based rewards. So put simply if you are lacking sleep you'll see food, particularly high-calorie food, as being inherently more rewarding due to greater activation of your anterior cingulate cortex. And if we follow the authors further down this garden path we note that lack of sleep leads to a greater desire for food, which leads to us gaining weight, which leads to sleep apnoea, which leads to subsequent bad nights' of sleep. Which as you can see is a vicious, vicious cycle.

Waking up to alarming news


Now before you're left with the impression that these researchers are little more than sleep-depriving sadists perhaps we should have a quick look at some of the work they've been doing to help us all sleep that little bit better. Or wake up better as the case may be. Yes, those scientists of siestas have finally developed an alarm clock which will put our mornings of swatting at the snooze button to bed, once and for all. The clock, which you set to wake you up as normal, begins to monitor your brainwaves 90 seconds before the alarm is due to go off. If the clock notices that you are in the deeper stages of sleep (stages three and four) then it will quietly self-snooze and check in on you later, waking you up with a refreshing glow only when you re-enter the lighter sleep of stages one and two. Of course like all new technology this brain-scanning alarm clock will take some time to adjust to, after all the wait between your alarm time and the time you enter those lighter sleep stages might just result in you being late for work. Something which is sure to detract from that good night's sleep no matter how smoothly you were woken. And then there's the issue of the EEG cords. It's probably not every night that you hook your scalp up to your clock using  electrodes. Then again maybe it is, I'm not here to judge.          


Sources

  • Benedict, C., Brooks, S., O'Daly, O., Almen, M., Morell, A., Aberg, K., Gingnell, M., Schultes, B., Hallschmid, M., Broman, J., Larsson, E., & Schioth, H. (2012). Acute Sleep Deprivation Enhances the Brain's Response to Hedonic Food Stimuli: An fMRI Study Journal of Clinical Endocrinology & Metabolism DOI: 10.1210/jc.2011-2759
  • Sylvia, J., Swittens, J., Komalavalli, R., Devi, C., & Manikandan, R. (2011). Alarm clock using sleep analysis International Journal of Biomedical Engineering and Technology, 7 (2) DOI: 10.1504/IJBET.2011.043176
  • Yoo SS, Gujar N, Hu P, Jolesz FA, & Walker MP (2007). The human emotional brain without sleep--a prefrontal amygdala disconnect. Current biology : CB, 17 (20) PMID: 17956744

Images

This post was written by Andrew Watt for A Hippo on Campus.

2 comments:

  1. I don't think that I fit any kind of usual sleep pattern. I am a retired widower, living alone, so I don't have to follow any regular schedule of sleeping and waking. And I don't.

    All around the clock, day and night, I tend to sleep for just an hour or two, then stay up for a few hours, usually reading on the internet. I've had this pattern for years.

    Is my sleep pattern causing me to have health problems? In my opinion, no. I am overweight, with type 2 diabetes, but I was that way years ago, when I followed a more usual sleep pattern.

    ReplyDelete
    Replies
    1. Hi Jim,
      Thanks for your comment. This research is still very much in its infancy and has thus far only focused on a complete lack of sleep rather than disrupted sleep or polyphasic sleep, which by the sounds of things is your prefered pattern of sleeping. Its fairly unlikely that disrupted sleeping patterns alone would be sufficient to result in significant weight gains, but instead they may be just one more reason for why weight gain occurs.
      With regard to polyphasic sleeping (sleeping multiple times over a 24hr period) there is currently not enough research out there to indicate whether similar associations between health and disrupted sleep exist. Having said this I've no doubt that it's only a matter of time before new research will enlighten us all.
      Thanks again,
      Andrew

      Delete