Sleep loss or inadequate sleep is a common problem in modern urban society, not often discussed.
The recommended normal sleep should be for 8 hours. Less and even more is not good for health.
Besides irritability, swings in mood, lack of concentration and a reduced sex drive it leads to many serious health hazards.
Several scientific studies from different ethnicities as varied as Japanese, Caucasians and Asians have found it to be related to high blood pressure (Hypertension), heart diseases linked to blockages of arteries and diabetes .
It has also been estimated that the risk of death from heart disease, cancer, stroke and all the causes combined death rates were lowest in persons sleeping for 7 to 8 hours per night.
Men and women both sleeping for 6 hours or less or 9 hours or more had 1.7- and 1.6-times higher death rates respectively as compared to those sleeping for 7 to 8 hours per night.
Sleep deprivation and hypertension:
The prevalence of hypertension is going up despite earlier diagnosis, better awareness, safer drug combinations. This has a direct bearing with adverse life style and which includes progressive reduction in sleep hours.
This relationship is very glaring in subjects 30 to 60 years of age and not so in people between ages of 60 and 86 years of age
This can be attributed to changes in the control of the nervous system called autonomic dysregulation that leads to increase in the sympathetic tone. In studies employing 24 hours ambulatory BP monitoring, the BP had a tendency to be higher on the day following sleep deprivation in both normal and patients with hypertension.
Japanese scientists have shown a significant increase in BP and urinary excretion of catecholamines in the evening after a sleep deprivation in a study in technical workers. Similar results have been shown by workers from several countries around the globe.
Elevated levels of a bio-marker C reactive protein (CRP) which indicates systemic inflammation have also been studied in sleep deprived individuals. An American study measured the hs CRP(High sensitivity CRP) levels for several days in healthy adults who stayed awake for 88 hours. They found both the hs CRP levels to be high along those with high BP in these individuals. The elevation of this marker represents vascular damage to blood vessels and is a risk factor for heart attacks and stroke.
Additionally sleep deprivation can induce long-standing psycho-social stress which again can lead to increase in salt intake and reduced salt excretion. These processes of retaining more fluid can be associated with arterial remodelling (change in structure and function of arteries) leading to high BP.
Sleep deprivation of diabetes:
Way back in 1999 a study carried out in young men to assess the hypothalamo-pituitary- adrenal axis (a complex set of interaction between parts of brain and suprarenal gland) found that after 6 consecutive nights of 4 hours in bed and then 12 hours of bed for 6 nights the glucose tolerance was reduced along with increased cortisol levels and also raised catecholamine levels. The increase in sympathetic tone also inhibits pancreatic function
Likewise, several studies including a pivotal study in year 2006 from Massachusetts, USA reported two times higher risk of developing diabetes in persons sleeping less than 5 to 6 hours of sleep.
Interestingly persons sleeping more than 8 hours per night had three times higher risk of developing diabetes during the long term follow up. This again shows a U-shaped relationship for developing diabetes like for getting hypertension.
Sleep deprivation and adverse cardiac events:
Several prospective studies from Europe, Japan and the United States have shown higher mortality rates because of heart related issues, especially heart attacks in persons working for prolonged hours 11 to 12 hours a day.
In the well-known Nurses' health study carried out in female health workers aged 45 to 65 years of age, individuals sleeping for less than 7 hours and those sleeping for 9 hours or more had incidence of heart related vascular problems significantly more than those sleeping for around 7 to 8 hours per night. This again shows a U-shaped relationship between sleep duration and adverse cardiac events.
The explanations for this association could lie with higher chance of getting hypertension, increased heart rate, constriction of blood vessels as well as retention of salt and water in the body.
Recent studies have also shown disturbances in the circadian rhythm, a cycle of physical, mental and behavioural changes that follow a 24 hours cycle. These natural processes respond basically to light and dark and affect both the animal and plant kingdoms.
Melatonin is a key hormone produced by the hypothalamus, a part of the brain, regulating day and night cycles. A deficiency of it can also result in disturbances leading to adverse events like high BP and diabetes and eventually to heart related issues. Recent evidence supports those circadian disturbances that occur before the development of hypertension and diabetes.
What is optimal sleeping duration and the remedies for getting it:
Sleep deprivation is an important risk factor for developing hypertension, heart disease and diabetes . The day after sleep deprivation, the sympathetic nervous system by releasing catecholamines increases BP.
This along with promoting several other risks like increased CRP, cortisol levels and reduced melatonin levels from the brain lead to ill health which eventually may shorten life span. Seven to eight hours is the optimal sleeping duration at night.
This can be achieved by sticking to a sleeping scheduled. Paying attention to what one eats and drinks and avoiding large meals within a couple of hours of bedtime. Taking alcohol for sleep is not recommended.
It may induce sleep but leads to disturbances after its effect has worn out. Melatonin is a safe agent to regulate diurnal variation especially in individuals who travel to different time zones frequently.
Creating a restful environment, use of room darkening shades, using relaxing techniques are some tips. Regular physical activities but not too close to sleeping time is also recommended.
Worries should be managed before going to bed. It is a good suggestion to write about the unfinished work and set it aside for the next day.
Recent scientific data confirms that sleep disturbances which are common are associated with several medical issues.
High blood pressure, heart diseases and diabetes are the common accompaniments. The optimal sleeping time is 7 to 8 hours every night.
Shorter periods as well as longer hours are associated with a U-shaped relationship which needs to be remembered. Getting good sleep is critical for heart health and how to get it needs an individualised approach.
The author is founder Director Gauri Kaul Foundation. Recipient of Dr B C Roy Award and Padma Shri.
Disclaimer: The views and opinions expressed in this article are the personal opinions of the author.
The facts, analysis, assumptions and perspective appearing in the article do not reflect the views of GK.