6. In Bed By 10:30pm. 


3.5 minute read... What has sleep got to do with losing weight you might be thinking? Well you might be surprised to hear that it has EVERYTHING to do with your weight loss success...!

Sleep is now thought of as the number one factor in any weight loss programme, even above diet and exercise! Your diet and exercise can all be in place but if your sleep is not then you could be seriously limiting your fat loss potential.

Insufficient sleep and late bed time (both independently of one another) are associated with obesity and there is a mountain of evidence out there showing that poor sleep habits have a detrimental effect on your hormones, your physical and mental health, your pain sensitivity, your strength, your cognition not to mention your waist line.

Poor sleep quality and duration will result in an elevation of the stress hormone cortisol and we already know that cortisol stores belly fat.

Poor sleep quality or simply a lack of sleep results in your hunger and satiety hormones (Leptin and Ghrelin) going out of whack so you'll feel more hungry the next day making it more difficult to control your food intake. Insulin levels will be higher and so will your cholesterol levels and blood pressure, which over time can lead to the development of Insulin Resistance, Type 2 Diabetes, Hypertension, Hyperlipidaemia (high cholesterol), Metabolic Syndrome and even depression and if you're a man, your testosterone levels will tank resulting in muscle loss.

And by lack of sleep, we're not even talking about getting 4 or 5 hours, a 2018 study[1] showed that just 1 hour of sleep restriction on five nights a week led to less proportion of fat loss in individuals undergoing calorie restriction than the group that had a full night's sleep despite similar overall weight loss by the end of the 8 weeks.

So although both groups lost about the same amount on the scales, the sleep restricted group lost more muscle and less fat! Interestingly, the sleep restricted group were allowed "catch-up" sleep at the weekends but even despite getting a few extra hours of sleep in they still lost more muscle and less fat by the end of it.

Similar results were seen in a study 8 years earlier[2], where both groups lost the same amount of scale weight but the less sleep group only lost 20% of that 3kg from fat and 80% lost from muscle! Here's an info graphic of that study:

A large 2018 study (91,000 people) from Lancet Psychiatry[3] found that people with a disrupted body clock (highly active at night or inactive in the day) had higher rates of major depression, bipolar disorder, more loneliness, lower happiness, worse reaction times and more mood instability. And we all know what happens to your healthy eating attempts when you're feeling down and depressed - where's my comfort food!?

The time you go to bed matters just as much as the duration of sleep. A study from researchers at U.C. Berkeley and Columbia University[4] suggests that with every hour of later bedtime, that Body Mass Index (BMI) goes up. Studying 3,342 adolescents from 1994-2009, they found that each hour of later bedtime on a school/work week was associated with a two-point increase in BMI. And this effect was true for people that got a full 8 hours of sleep, and the results were completely independent of TV time or exercise.

Ideally you'll want to be in bed by 10:30pm at the latest to catch 5 sleep cycles which occur around every 90-110 minutes. That's where the 7-8 hours of sleep recommendation arose from. When you are exercising intensely AND in a calorie deficit this is added extra stress for your body so you'll need more sleep/recovery time, therefore aiming for the 8 hours as opposed to the 7 hours would be advisable.

If you're not getting to bed until midnight or later, but having to get up early for work/kids etc, you're missing out on 1 or even 2 sleep cycles which is going to hamper your body's ability to recover and repair itself.

Then another late night... and impaired recovery again but you've not fully recovered from the workout from the day before yet so you get a compounding effect and eventually you get so tired that you reach burnout and lose all the will to exercise. Your pain tolerance will drop so you'll be more likely to experience general aches and pains which will also do your motivation to be physically active no good either.

Over a matter of days, these poor sleep habits will cause hormonal imbalances; keeping cortisol levels high which can contribute to fat accumulation around the midriff; chronic fatigue and a number of other health issues as already mentioned above, along with disrupting your hunger and satiety hormones forcing you to crave junk food thus making it very difficult to control your appetite and eat healthy.

Poor sleep will also lead to more joint aches and pains because your pain receptors (nociceptors) become hyper-sensitised[5]. In addition to increased pain sensitivity, you'll experience more muscle weakness, tightness and muscle cramps because when the nociceptor sensitivity goes up, the sensitivity in the muscle sensors (mechanoreceptors) goes down, resulting in muscle inhibition.

So your mission, if you choose to accept fat loss (and optimal health!), is to get to bed no later then 10:30pm on at least 4 nights this week. Don't believe this will make a difference? That's OK, all I ask of you is that you just suspend disbelief right now and try it and see how much energy you have accumulated by the end of the week, how amazing and unstoppable you feel, how much weight you've lost and just how lose those jeans feel...! Once you've gotten into the habit of 4 nights at 10:30pm add in a 5th, then a 6th ultimately making late nights a rare exception rather than the norm.

The topic of sleep is so important for your fat loss and your general health that over the course of this week I'll be sharing with you lots of tips and tricks to help you improve your sleep and really get a handle on this because I know a lot of people struggle with their sleep...


[1] Wang X, Sparks JR, Bowyer KP, Youngstedt SD. Influence of sleep restriction on weight loss outcomes associated with caloric restriction. Sleep. 2018;41(5):10.1093/sleep/zsy027. doi:10.1093/sleep/zsy027

[2] Nedeltcheva AV, Kilkus JM, Imperial J, Schoeller DA, Penev PD. Insufficient sleep undermines dietary efforts to reduce adiposity. Ann Intern Med. 2010;153(7):435-441. doi:10.7326/0003-4819-153-7-201010050-00006

[3] Lyall LM, Wyse CA, Graham N, et al. Association of disrupted circadian rhythmicity with mood disorders, subjective wellbeing, and cognitive function: a cross-sectional study of 91 105 participants from the UK Biobank. Lancet Psychiatry. 2018;5(6):507-514. doi:10.1016/S2215-0366(18)30139-1

[4] Asarnow LD, McGlinchey E, Harvey AG. Evidence for a Possible Link between Bedtime and Change in Body Mass Index. Sleep. 2015;38(10):1523-1527. Published 2015 Oct 1. doi:10.5665/sleep.5038

[5] Campbell CM, Buenaver LF, Finan P, et al. Sleep, Pain Catastrophizing, and Central Sensitization in Knee Osteoarthritis Patients With and Without Insomnia. Arthritis Care Res (Hoboken). 2015;67(10):1387-1396. doi:10.1002/acr.22609