The Impact Of Sleep Duration On Energy Levels, Exercise Capacity And Health

The most popular reason for avoiding the gym is being ‘too tired’.

It is becoming increasingly common among the general population to experience regular sleep loss due to long work hours, hectic schedules and constant on-the-go lifestyles. In just the last 100 years, the average time spent sleeping in each 24 hour period has decreased by 1.5 hours! Why am I relaying these facts to you? We all know how important regular exercise and healthy eating is to our health but in neglecting our body’s need for sleep we are hindering the progress of our physical performance, weight management and overall well-being.

Disturbed sleep is common with ~40% of us suffering from some form of sleep disorder meaning that we never get a proper nights rest even if we spend the recommended 7-9 hours in bed every night. The main issue with sleep disorders is that they tend to be chronic and 56% of people affected by them will continue to have symptoms for years.

Sleep and health have a vital relationship. The more you take care of your health, the more likely you are to have a restful night’s sleep. Similarly, the better your sleep duration and quality of sleep, the healthier you are likely to be.

Sleep and exercise may seem mediated by completely different physiological mechanisms but there is growing evidence of a vital relationship between the two. If you do not get enough sleep on a regular basis you risk losing your motivation, energy levels and ability to recover from exercise.

General Health And Sleep Duration

Sleep deprivation, disrupted sleep, fatigue and insomnia are associated with the following:

-          Hypertension/high blood pressure

-          Above normal resting heart rate

-          Decreased immunity – increased susceptibility to illness

-          Decreased cognitive function

-          Mood swings

-          Decreased energy

-          Increased risk of developing depression

-          Increased risk of developing a chronic disease

Deteriorating sleep as we age also prevents us from storing memories. The slow brain waves generated during sleep transport memories from the hippocampus to the prefrontal cortex which acts as a long term storage depository for memories. A poor quality of deep sleep/reduced time spent in deep sleep means that memories are overwritten by new memories before they can be stored for the long term.

How Sleep Affects Exercise

Sleep restriction has been found to significantly decrease physical activity levels the following day. It has a negative effect on both the duration and average intensity of your workout. If you are working towards a goal (and who isn’t), it is likely to hinder your progress. If you manage to push past the fatigue you are feeling, you are more prone to injury.

Sleep deprivation results in an increase in blood pressure and decrease in muscle sympathetic nerve activity. It can also affect the way you respond to stress both physically and mentally. As you can see, if you don’t have enough sleep, the gym is really not going to benefit you in the way it would should you be well rested.

If you are finding it difficult to sleep, try using Optimum Health Ultimate ZMA. This natural supplement is ideal for improving sleep, increasing strength gains and aiding recovery after exercise. It can also positively affect your libido!

How Exercise Affects Sleep

Vigorous exercise in the three hours leading up to bed will actually make it harder for you to fall asleep. It raises the core temperature and stimulates your heart, brain and muscles into a surge of activity. Exactly the opposite of what you need before trying to sleep!

Exercise in the morning can help relieve stress and put you in a good mood for the rest of your day. In order to reap the full benefits of training, complete your workout outside. Exposure to natural light when you wake up will help you to sleep better at night by reinforcing the sleep-wake cycle.

The most effective way to get a good night’s sleep by exercising is to hit the gym late afternoon/early evening and go all out! This will raise your core temperature a few hours before bed, allowing it to fall at the optimum time as you get ready for bed.

A number of studies have found that both acute and long term exercise increase slow-wave sleep, total sleep time and decrease the sleep latency period (time it takes to fall asleep). A little exercise every day will make a difference. Good sleep and exercise routines will help you feel energised! The hardest part is getting started. Once you find a routine which works for you, stick to it and see how much better you feel!

The National Sleep Research Project has published these helpful facts:

  • 17 hours of sustained wakefulness leads to a decrease in performance equivalent to a blood alcohol level of 0.05%.

This explains why you feel a little clumsy and light-headed when you don’t get enough sleep. Not only should you aim to get sufficient sleep each day, you should avoid long periods of being awake. We are more vulnerable to this at the weekend when we try to make the most of our free time!

  • Feeling tired can feel normal after a short time. Those deliberately deprived of sleep for research initially noticed greatly the effects on alertness, mood and physical performance, but awareness dropped off after the first few days.

If you are one of the unlucky people suffering from disturbed sleep, it is likely that you are now used to feeling low in energy and lacking in motivation. You don’t have to put up with this. Just a few simple changes to your fitness and sleep routine and these negative feelings can be left in the past.

  • Anything less than 5 minutes to fall asleep at night means that you are sleep deprived. The optimum time frame is between 10 and 15 minutes.

If you fall unconscious the moment your head hits the pillow you are more likely to sleep lightly and not get the full rest that you need to feel energised the following day. Facts about naps are listed below this section and can help you to avoid this.

  • The sleep that we need is unique just like we are. Between 7-9 hours is recommended for adults but this is not true for everybody. Studies have shown that less than 5 hours is detrimental to health. There is no conclusive evidence to support the theory that too much sleep has a negative impact on us!

The important thing is to establish a regular sleep cycle and gage how much sleep dependent on how you feel and how you perform. Weight gain can also be a sign too! If you find yourself gaining weight it may be a sign that you are having insufficient sleep.

Facts about Napping:

  • Sleep deprivation impairs performance more significantly between the ages of 18 and 24 than at any other age.
  • A prophylactic nap (power nap) helps to increase alertness for up to 10 hours.
  • Naps at lunch time or in the early afternoon are great! Your body tends to feel tired at this time and it is unlikely to interfere with sleep that evening. The Romans used to nap at this time everyday and they managed to live a highly productive lifestyle (some of them anyway).
  • If you nap for longer than 45 minutes you risk sleep inertia. This is the sluggish feeling you get when you wake up and can last for 30 minutes or more.
  • There is such a thing as the NASA nap. Now if I was going to believe any recommendations, it would probably be the one coming from NASA! The NASA nap is a 26 minute nap which has been found to increase performance by 34% and alertness by 54%.


Briones B, Adams N, Strauss M, Rosenberg C, Relationship Between Sleepiness and General Health Status, Journal of Sleep Research and Sleep Medicine, 1996, 19(7): 583-8.

Oldham J, Sleep and Exercise, Journal of Psychiatric Practice, 2006, 12(4):201.

About the Author

Job Role Sports Nutritionist and Social Media Coordinator Qualifications Bsc Sport and Exercise Science Steph has a competitive athletic background which spans 19 years. As a child she performed with the English Youth Ballet and had performed on the West End stage by the age of 10. Her enthusiasm for sport and fitness continued to grow as she did, encouraging her to learn more about nutrition and training. She began using her knowledge and personal experience to help others when she began coaching at the age of 16. From here, she went on to study Sport and Exercise Science at the University of Essex during which time she also received the Most Promising Newcomer Award from her University to mark her outstanding contribution to sport. During her first year of study she was introduced to partner stunt acrobatics and artistic gymnastics. After one year of dedicating herself to a lifestyle revolving around her sport, she was training with the best team in the UK who are currently ranked fifth in the world. Steph has worked in both the private and public sector coaching children and adults from grassroot to elite level as well as providing them with cutting edge advice on how to reach their goals. Steph has received awards for her choreography and has competed nationally and internationally meaning that she can back up her scientific knowledge with a wealth of experience. As our resident Sports Nutritionist, Steph is here to provide the most current and evidence based fitness, health and nutrition information to help you reach your health and fitness goals.


  • July 7, 2013 Tamatha Alires

    For years, doctors have warned about the dangers of not getting enough shuteye -- traffic accidents, weight gain, decreased productivity and immune protection, but the effects of oversleeping are not well-understood. There isn't medical evidence to recommend that people who sleep long hours should change their habits.

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