Margaret Thatcher supposedly said that ‘sleep is for wimps’, while Donald Trump, who similarly sleeps just four hours a night, advises ‘don’t sleep more than you have to’.

Perhaps they share the rare gene DEC2 which means they require less sleep than most. About three in 100 people have this recently discovered gene, but the rest of us are predisposed to needing between seven and nine hours’ sleep every night. Though our needs vary across age groups and are affected by lifestyle.

The cumulative long-term effects of sleep disorders are associated with a wide range of negative health consequences, including an increased risk of hypertension, diabetes, obesity, depression, heart attack and stroke.

There is also a host of short-term effects, which include cravings for fatty and sugary foods, weight gain, decreased libido, dull skin, puffy eyes, anxiety, low mood and a reduced immune function.

Mentally, we feel drowsy and less alert during the day, which is primarily due to a lack of REM (rapid eye movement) sleep. This is the part of our sleep cycle when we dream the most. It is also the part responsible for memory co-ordination, creativity and restoring our mind, enabling us to learn complex tasks. Children, in particular, need REM sleep for brain development. 

Are you sleep deprived?

One way of working out if you are sleep deprived is to take the Sleep Onset Latency Test, which was developed by Nathaniel Kleitman from the University of Chicago. It checks for excessive daytime sleepiness, so needs to be done in a quiet, dark room in the afternoon.

Lying on your bed, place a metal tray on the floor next to the bed and hold a spoon over the edge of the bed above the tray. Check the time and close your eyes. When you fall asleep, the spoon will fall out of your hand, hit the tray and wake you.

Falling asleep within five minutes means you are severely sleep deprived; five to 10 minutes means you probably aren’t getting enough sleep. If you are worried the spoon will miss the tray, set your alarm for five minutes and see if you fall asleep before it wakes you up, to check if you are sleep deprived.

Dozing detoxes the brain

Apart from the long-term physical impact of sleep deprivation, scientists are now considering the influence of inadequate sleep on the health of the brain and, in particular, the detoxification of the brain.

Our brain accounts for just 2% of body weight and yet uses up 25% of the body’s energy. It produces a great deal of waste material that needs to be removed or drained out of the brain.

Scientists have discovered that the brain’s drainage system is 10 times more active during the night than in the day. This has lead sleep specialists to conclude that one of the roles of sleep is to dispose of the metabolic waste that accumulates while we are awake.

One of the toxins produced in the brain is a protein called beta-amyloid that, when allowed to build up, can produce plaques which collect around the brain’s nerve cells. It is these beta-amyloid plaques that are associated with Alzheimer’s disease. It is not clear whether amyloid protein build-up is due to over-production, a lack of clearance or both.

However, research published in Brain magazine earlier this year has shown that beta-amyloid concentration is reduced during the periods when we are asleep and is highest when we are awake. This suggests our sleep/wake cycle effects changes in beta-amyloid concentrations.

It is well known that those who suffer from Alzheimer’s disease have higher levels of fragmented sleep than those who don’t have the disorder. So, given the evidence that sleep is associated with toxin elimination, does this link go both ways? Does poor sleep lead to Alzheimer’s disease?

Or, within the pathology of cause and effect, is it the plaques seen in Alzheimer’s disease that cause sleep disruption?

More research is needed before we can say for sure that poor sleep influences Alzheimer’s pathology. As with many health concerns, prevention is the key aim, so ensuring consistent sleep quality is the goal.

Early intervention to improve sleep and maintain healthy sleep in those exhibiting early signs of Alzheimer’s disease could help to prevent or slow its development.

15 signs you’re not just a bit snoozy, you need to sleep more

Not only do sleep problems cost the NHS millions in treatment each year, there is also a huge cost to industry in terms of lost productivity. So, how can you tell if you are sleep deprived rather than just a bit tired? Look out for these tell tale signs…

1. Always needing an alarm to wake you up at the right time
2. Finding it difficult to get out of bed in
   the mornings Falling asleep in the cinema, or after yoga
3. Experiencing tiredness while driving
4. Using coffee to get you going in the morning
5. Being cranky and having a shorter fuse than normal
6. Having reduced self-control, being more impulsive in general and less inhibited in social situations
7. Suffering concentration lapses at work and using social media more
8. Experiencing poor memory retention
9. Becoming clumsier than usual, tripping over more and having reduced reaction times
10. Losing balance emotionally, with increased anxiety, sadness or anger
11. Being less alert and finding it hard to concentrate and trouble-shoot problems
12. Making poor decisions as your higher-level cognitive processing is affected
13. Relying on long weekend lie-ins of around 10 hours to catch up on sleep
14. Finding it hard to judge social situations and isolating yourself more
15. Falling asleep in less than five minutes. According to the Sleep Foundation, it should take between 10 and 20 minutes

Read more: How to sleep better