You’ve heard it since you were a kid, get a good night’s sleep and you’ll feel better in the morning.

But why is this the case?

What is it about sleep that makes it so useful?

And as adults do we need sleep as much as we did?

Hopefully this article will address these questions and give you three good reasons why you should be sleeping more.

Reason #1. Increased Testosterone and Growth Hormone

The two most commonly abused drugs in bodybuilding are testosterone and growth hormone, two hormones that can;

  • Increase muscle size
  • Increase strength
  • Lower body fat

There are many ways to naturally boost both of these hormones but sleep is probably the easiest.

Studies have shown that a bad night’s sleep can drastically reduce testosterone levels the morning after [1], ergo more sleep equals more testosterone.

Growth hormone is maximally released whilst you are sleeping [2], meaning that if you sleep longer (and better) then you will release more growth hormone.

Incidentally this is why children (particularly teenagers) require more sleep than adults, but it’s also a good reason why adults should prioritize sleep if they are trying to build muscle.

Reason #2. Improved performance in the gym, playing field, and at work

In 2011 Mah et al looked at the benefits of sleep on collegiate basketball players, they found that increasing sleep led to improved athletic performance, mood, and reaction time.

The study concluded that peak performance could only be reached when optimal sleep had occurred [3].

If you are playing some form of sport and you want to get the most out of yourself, then sleep more.

Obviously this can also affect your performance in the gym, if you want a new 1RM on the bench press then you’ll want 8 hours plus of sleep.

Cognitive Performance

Interestingly though, sleep doesn’t only improve physical performance but also cognitive performance (brain power).

A bad night’s sleep can affect

  • Short and long term memory
  • Influence decision making skills
  • Ruin concentration [4].

The old saying that getting a good night’s sleep is better than staying up late cramming for an exam is clearly correct!

Reason #3. Bad sleep can lead to overeating and weight gain

While we’ve been exclusively looking at the positives of a good night’s sleep so far, we’re now going to turn our attentions to one of the biggest downsides of a bad night’s sleep.

In reason #1 we looked at how sleeping can influence certain hormones (testosterone and growth hormone), but these aren’t the only hormones that can be affected.

A study by Taheri et al (2004) found that a short sleep duration could lead to reduced Leptin and increased Ghrelin which causes weight gain.

Leptin is a hormone that tells your body when you are full, it is usually released after a meal and is the signal to stop eating.

Ghrelin is a hormone that tells your body that you are hungry, if you’ve ever suffered hunger pangs then you can blame Ghrelin.

So you can see why increased Ghrelin, and lowered Leptin can lead to a person eating more, but this isn’t the only cause of weight gain.

As crazy as it sounds, just the act of being awake longer can lead to increased calorie consumption – because if you’re awake you are capable of eating, so the longer you are awake the more time you have to eat!

The final way that a bad night’s sleep can cause weight gain is through fatigue. The less energy you have, the less energy you can expend.

You will walk less, and fidget less, you’ll probably accomplish less tasks, and in general you’ll be burning less calories – whilst eating more.

Big Problem

Big problem. So if you have trouble sleeping and managing your weight, often times supplementing with a sleep aid can help tremendously.


If you are trying to improve your health or body composition then the simplest way to do so is to improve your sleep quality and duration. Try going to bed half an hour earlier than usual, invest in a decent mattress, and consider taking supplements that can improve sleep (ZMA being the most commonly used one). Also, try to go to sleep and wake up at the same time every day your body loves routine and will respond favourably to this.


[1] Goh, V. Tong, T. 2010, Sleep, sex steroid hormones, sexual activities, and ageing in Asian men. Journal of Andology 31(2): 131-7

[2] Born, J., Fehm, H. 2000. The neuroendocrine recovery function of sleep. Noise Health 2(7): 25-37

[3] Mah, C., Mah, K., Kezirian, E., Dement, W. 2011. The Effects of Sleep Extension on the Athletic Performance of Collegiate Basketball Players. Sleep 34(7): 943-950

[4] Alhola, P., Polo-Kantola, P. 2007. Sleep deprivation: impact on cognitive performance. Neuropsychiatric Disease & Treatment 3(5): 553-567

[5] Taheri, S., Lin, L., Austin, D., Young, T., Mignot, E. 2004. Short sleep duration is associated with reduced Leptin, elevated Ghrelin, and increased body mass index

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