Sleep is a basic need for humans and for most animals. It is not rest as some people think because the brain is actually very active during sleep. During the first year of life, the requirement is around 16 hours per day. The need gradually reduces with age to around 8 hours a day for adults. Older adults need a total of around 6 hours per day. Less or more sleep than this can have impacts on the mind and body.

Sleep is studied using electrical recordings of the brain waves called the EEG. Sleep has been classified into two types – Non-REM Sleep and REM (Rapid Eye Movement) sleep. The Non-REM type of sleep has three stages of which stages 1 and stage 2 are commonly known as ‘light sleep’, whereas stage 3 is also ‘deep sleep’. Alternating with Non-REM sleep is the REM type, which is also called ‘paradoxical sleep’ because the body activity is found similar to a state of being awake.

The REM sleep is also popularly termed as ‘dream sleep’ as dreams are experienced predominantly in this stage. Adding the time spent in both Non-REM and REM sleep gives the total sleep duration. There is a lag period between going to bed and going to sleep, which is called sleep latency. Sleep efficiency is the total sleep duration out of the time spent in bed. Sleep begins when the person goes into non-REM stage 1 sleep. During this transition, individuals may experience body jerks, hear, or visualise unusual sensations, which are considered normal.

Stage 1 amounts to only five per cent of total sleep and so it is just a brief transit stage. The non REM Stage 2 is where a person’s brain waves become slower; people spend nearly half of their total sleep time in this stage. Some people may grind their teeth during this stage, and if persistent, they must seek help. After this, a person moves into Non-REM Stage 3, where the waves become very slow. This is a state of deep sleep, and makes up 20-25 per cent of total sleep period. This stage dominates in the first half of sleep. When woken from this stage, it takes relatively longer to get a sense of surroundings.

There could be bouts of scary dreams during this stage called terrors, which cannot be recalled. Abnormal behaviours of sleep such as walking and talking can occur in this stage. Some individuals may complain of inadequate sleep if they have not got a sense of having slept in stages 1 and 2. After Stages 1-3, it is back to stage 2 and stage 1, before transition to REM sleep.

The first REM sleep is of about 10 minutes and its first appearance on time and its duration has mental health significance. After going through all the 4 stages of sleep, one cycle of sleep is said to be completed and this usually takes 90 to 120 minutes. A person needs four such cycles in continuity to complete the total sleep duration.

Amount of REM sleep increases with time and this sleep dominates the latter half of sleep. So, dreams occur mostly in the early morning hours. There is a definite pattern or architecture for sleep and determines the sleep quality. The parameters to assess sleep quality include total sleep duration, sleep latency, sleep efficiency, percentages of deep sleep and dream sleep. Sleep also correlates with the body metabolism occurring at night. The hormone melatonin starts to increase before midnight and cortisol hormone increase occurs closer to morning time.

There is an internal biological clock, which means the ideal time for sleep is between approximately 10 p.m. and 7 a.m. One should follow this biological clock. But it is inevitable for some people to work night shifts; they need to ensure quality sleep during other times. Frequent and persistent deprivation of sleep can make a person angry, lose concentration, impair memory function, and thus worsen mental health and behaviour. Therefore, studying through the night is generally not recommended as it can hamper comprehension of what is being read.

Quality night sleep helps in memory consolidation, which means there must be adequate night sleep after having read for a long time to help the learning register. If sleep gets deprived one day, the sleep architecture for the following day modifies itself. For example, there can be early appearance of REM sleep. There is no need to cover up the hours of sleep lost on a previous day.

However, some individuals may feel the need to repay sleep debt by sleeping extra hours over the weekend. Individuals having gone through all the stages of sleep for the appropriate duration are likely to wake up feeling fresh. In contrast, if they have not gone through the stages appropriately, they are likely to wake up feeling upset, irritable and it takes a while for their emotions to become stable.

Low mood in the morning hours or early waking up, about two hours earlier than usual, are common features of depression. Sleep pattern disturbance is one of the first few problems experienced during onset or recurrence of some severe mental disorders. If the person is not getting enough sleep persistently, termed ‘insomnia’, this should warrant early consultation with their physician or psychiatrist.

Isolated sleep problem can be considered only after ruling out common illnesses. So, simply taking a sleeping pill for a brief period may not help many people. Some people may even become addicted, which then can become difficult to treat. There are better ways to manage insomnia than relying on sleeping pills. Insomnia can also occur in several physical health issues such as diabetes, hypothyroid, Parkinson’s disease and sometimes due to excess medications in elderly people that may cause drug interactions.

Stress at work, problems with family members or others, issues related to financial difficulties, property disputes, failure to achieve, loss of relatives, physical illnesses and many other stressful events give rise to mental health problems, where insomnia or excessive sleep can be a feature. In persons with so called ‘bipolar illness’, a mental disorder, insomnia is either an early sign or itself can trigger an episode of ‘mania’.

Generally, the first best thing to do is to restore normal sleep duration and quality to help stabilise the mood. Usually this can be triggered by an episode of stress or discontinuation of medications. In other chronic mental illness like schizophrenia also, improving sleep improves behaviour significantly. Some medications prescribed for mental illnesses can induce excessive sleep, which also takes away the quality of life of the person. However, there are many newer medications, which do not cause excessive sleep.

Dreams occur predominantly in REM sleep and can be recalled. Scary and worrying dreams are called ‘nightmares’. If nightmares occur frequently, it is better to consult a psychiatrist. During REM sleep, there is paralysis of all body muscles except around the eyes, which is kind of a safety mechanism so the person can dream but not act out. But in persons with so called REM Behaviour disorder, which may be an early sign of neurological illness, the person may act out by moving hands and legs.

Quality sleep improves mental health. Improved mental health means better functioning. Thus, as per this year’s theme, most people having better sleep and mental health, are likely to feel happy. Sleep must be respected. The brain is active and functioning during sleep. Sleep hygiene must be maintained. The unfortunate death of a world-famous pop star, who reportedly sought sleeping pills and more for chronic insomnia is a case study that should alert people who rely on sleeping pills or alcohol for good sleep. Spending more time in bed than required is not recommended.

Tips for sleep hygiene: ·

Use your bed to sleep at night ·Avoid sleeping during daytime ·Let your sleeping and waking times be the same every day ·Ensure the bedroom has minimal noise and lighting · Arguing before going to bed can hamper sleep ·Avoid clock watching if woken up or not getting sleep ·Worrying over not getting sleep does not help ·Exercise early in the morning or early evening, not before bedtime ·

Avoid excessive coffee or tea drinking ·Alcohol is never useful for sleep ·Smoking makes the brain active and prevents sleep initiation · Avoid the use of gadgets, laptops, or phones for long before bedtime · One could watch or read something that is boring to get early sleep initiation.

(The writer is a Bangalore-based consultant psychiatrist and has contributed this article on the occasion of World Sleep Day, which falls today.)