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Conception Mar 8, 2019
8 Minutes

Boys: if you ever needed a reason to sleep – its your hormones and sperm!

This article looks at the very dramatic effect sleep has on male hormones, sperm and what the latest science suggests is behind this. Most crucially it shows you some very small tweaks you can make to put yourself in a much better position for your health and fertility.


There are two things we are pretty sure about:

ONE: sperm counts have dropped very dramatically over the last forty years – down over 50% on average – that is a stratospheric fall by any account (click here for much more).

TWO: sleep deprivation is now being recognised as an increasingly common condition inherent within modern society, driven by artificial lighting and a ‘24/7 lifestyle’. In fact: ‘there is a 1-2hr difference of the sleep duration between people nowadays and those living 50-100 years ago. In fact, sleeping less than 6hrs or over 9hrs a night now accounts for about ⅓ of adults.’ (2)

Question is – are these factors linked?!

The answer is that research is increasingly suggesting: yes.

Here’s what you need to know about why sleep matters:

We know that sleep deprivation isn’t a good thing. Sleep loss is not only a social issue, but also leads to a large number of human disorders: including potential immune impairment, mood and hormone issues and male reproductive impairment. In fact it has been linked to issues with testosterone production in men. Testosterone production by the body being a key factor to produce adequate amounts of sperm. (1)

My attention was first drawn to the potential link between falling sperm count and sleep loss at a talk on male infertility by one of the leading experts in men’s reproductive health Pippa Sangster a consultant Urological Surgeon at UCL. She pointed out that there is a link here.

Question is: why is sleep so powerful when it comes to sperm and and how much sleep is too little? Or even too much?!

We know that too little sleep amongst other things can have an impact on our immunity and our mood. We also know that not only are we generally getting less sleep but that the ‘frequency of sleep disturbances has increased in the industrialised world during the past few decades.’ (1)

So how do you know if you’re affected, how do you define sleep issues and disturbances?

Well most studies count:

  • ‘short sleep’ as anything below 6 hours

  • average is between 7 and 8 hours

  • long is anything above 9 hours.

However, it isn’t just the length of time that is being implicated it is also ‘abnornal’ sleep patterns which are also on the rise.

What does that mean?

That can mean ‘late bedtimes’ (generally defined as post midnight) and variance in sleep schedule or ‘frequent shifts in sleep timing’ which have both been linked to potentially reducing depth of sleep, sleep quality and eventually to ‘metabolic problems and increased prevalence of depressive symptoms‘ when the occurrence is frequent. (1)

In a nutshell: if you’re regularly sleeping 6 hrs or less, 9 hrs or more and/or are going to bed late or with a varied bedtime you could be vulnerable.

Ok – so we know that our sleep is perhaps not the best – but what does the research suggest in terms of implications on sperm?

The results of several trials show a clear link between abnormal sleep and issues with sperm. Here are a couple of extracts to give you a picture – and it seems that too short and too long are equally guilty:

  • Sperm count: ‘our data revealed that the numbers of sperm cells in the semen and their survival rates were significantly lower in all of the short sleepers and most of the long sleepers, suggesting that reduction in the sperm cells depended on the length of sleep time.’ (1)

  • Sperm volume: ‘sleeping above 9 hrs = a 21.5% decrease in semen volume and 40% decrease in sperm number…sleeping less than 6.5hrs = 4.6% decrease in sperm volume and a 26% decrease in sperm count.’ (2)

  • Motility: the data showed that the proportion of progressively mobile sperm was significantly lower in all of the short sleepers and most of the long sleepers, which was identical to the results on the sperm count and survival.’

  • Late bedtime: ‘our data clearly show that late bedtime (post midnight) is associated with lower sperm counts and survival in all of the short sleepers and some of the average sleepers, suggesting late bedtime is an important factor….our results also revealed that a late bedtime reduced the number of motile sperm at both levels, suggesting that later bedtime lowered sperm movement. (1)

Ok so it seems that there is some connection here – question is:


Let’s start with Testosterone. A fundamental ingredient in order to produce enough sperm for a man. Unfortunately we know that issues such as endocrine disruptors (pesticides), weight gain (adipose tissue – ie. fat tissue – converting testosterone to estrogen) and stress (Cortisol’s impact on testosterone) are all modern factors that are playing a role interfering with testosterone and by default sperm – click here for more. However, sleep is another apparent dynamic.

‘Several reports suggest that sleep duration was associated with the testosterone levels in males.’ (2)

Here is what the research is saying:

Testosterone has its own ‘circadian rhythm’.

What does that mean? It means it has its own regular rhythm. When it comes to Cortisol: theoretically it should peak during sleep and then lower through the day beginning to rise again with the onset of sleep (3). Research is also suggesting that sleep does have an impact on testosterone levels. In fact ‘a recent study has shown that restriction of sleep time to 4.5hrs was associated with a lower morning testosterone level’. Testosterone levels have also been shown to reduce with increased awake time. In fact, restricting sleep for eight nights to 5hrs (between the hours of 00:30-05:30) a night reduced testosterone levels by 10-15%. (3)

How does this link to fertility?

Well we know that too little testosterone is going to give us issues with sperm production and one study in rats demonstrates this quite clearly with a significant fall in sperm motility and testosterone in sleep deprived rats. (4)

There also seems to be another reason….

Antisperm antibodies (ASA):

Now we do know that a lack of sleep can impact our immunity and there are a couple of studies that suggest this too can play a role in why a lack of sleep can potentially impact fertility.

What are Antisperm antibodies?

Well as the name suggests this is where your own body: ‘immune-reactive particles produced by the body as a response against the proteins contained in sperm. The antibodies target sperm in the body and destroy healthy sperm.’ (1)

Interestingly enough one study showed there was a relationship between insufficient sleep duration and increased antisperm antibody content. The results suggested that the proportion of individuals who were ASA positive was obviously higher in the short sleepers vs the others. ‘Strongly supporting that deficient sleep was a major contributor to presence of ASA in the semen.’ (1)

So what to do?

In those who had altered their sleep duration towards 7-7.5 hrs/day, increase of the semen parameters was found, further indications the sleep-semen association’ (2)

It sounds pretty obvious to say – but there is enough real science and research to suggest that actively making sleep a priority is the thing to do if you want to keep your hormones and swimmers in top condition.

The evidence suggests that restoring sleep cycles can have a beneficial effect and doesnt appear to be too difficult to do:

‘As little as three days of sleep extension may benefit insulin metabolism and increase testosterone in habitually short-sleeping men.’ (5)

I know the pace of life these days means that is sometimes hard to do, but really the 80s mantra of ‘sleeping when you’re dead’ has to beover. The reality is that not only do we need sleep for sperm but we need it for many aspects of our health – including hormonal balance, immunity and many more.

How do you do this?

If this is a lifestyle driven issue then the easiest thing to start with is to consciously decide to prioritise it. Have dinner earlier (better for your digestion also). Give yourself permission to look after your health and wellbeing. Be active in managing your life to accommodate a bedtime that isnt super late. Then there is the ‘blue light’ and 24/7 culture. It is time to get disciplined with yourself. Have a rule that you switch off electronics at least an hour before bed as research suggests that light and especially blue light suppresses the sleep hormone (melatonin) secretion. Make your bedroom a haven. Free of the TV, free of your phone and iPad. Go back to the good old book. Do whatever works for you in order to make sure you at least have the opportunity to get at least seven hours per night. It wont happen by itself however (especially not in our modern times with our modern pressures) so it has to be an active decision from you. Your body will thank you for it.


  1. LIU MM, LIU L, YU C-H: Sleep Deprivation and Late Bedtime impair sperm health through increasing antisperm antibody production: a prospective study of 981 healthy men. Medical Science Monitor: International Journal of Experimental and Clinical Research: 2017: 23: 1842-1848

  2. CHEN Q, YANG H, CAO J: Inverse U-shaped association between sleep duration and semen quality: Sleep Journal: 2016 Jan 1: 39(1): 79-86.

  3. WITTERT G: The relationship between sleep disorders and testosterone in men. Asian Journal of Andrology. 2014 Mar-Apr: 16(2): 262-285

  4. CHOI JH, LEE SH, SHIN C: Effect of sleep deprivation on the Male Reproductive System in Rats: Journal of Korean Medical Science: 2016: Oct: 31(10):1624-1630

  5. KILLICK R, HOYOS C, LIU P: Metabolic and hormonal effects of ‘catch-up’ sleep in men with chronic, repetitive, lifestyle-driven sleep restriction. Clinical Endocrinology: 2015: Oct 83(4): 498-507


This article is for informational purposes only. This article is not, nor is it intended to be, a substitute for professional medical advice, diagnosis, or treatment and should never be relied upon for specific medical advice. The information on this website has been developed following years of personal research and from referenced and sourced medical research. Before making any changes we strongly recommend you consult a healthcare professional before you begin.

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