In this chapter, the authors have discussed a detailed review on sleep, sleep disorders, and their diagnosis. This chapter provides an insight study of sleep, sleep illness characterized by The International Classification of Sleep Disorders (ICSD), factors affecting sleep, and types of sleep based on age group. Artificial intelligence and machine learning algorithms are also applied in recognizing sleep disorders based on EEG signal attributes. It also highlights the classification of insomnia using different classifiers such as support vector machine, decision tree, and deep neural network.
“Sleep that knits up the ravelled sleave of care, The death of each day’s life, sore labour’s bath, Balm of hurt minds, great Nature’s second course, Chief nourisher in life’s feast.” …Shakespeare, Macbeth10
TopIntroduction To Sleep
In a daily routine of a human’s life, sleep plays a very vital part. Almost every individual spends about one-third portion of their life-time in sleep. Eminence sleep and receiving sufficient amount of sleep at the exact time is as necessary and crucial to survival as food and water. Without sleep it’s difficult to form or maintain the pathways in the human brain which allows humans to acquire and generate new memories, and it’s tougher to focus and respond rapidly.
Good amount of rest for the body as well as the brain is very essential in order for the proper functioning of the nerve cells (neurons). In fact, there is a remarkably active phase between the brain and the body while human’s sleep. Many toxins are generated when a person is awake, sleep helps in removing these toxins.
Every individual human being requires a sufficient amount of sleep, but its biological purpose remains unidentified. Insufficient volume of sleep affects most of human organs namely the brain, heart, and lungs, and also leads to improper functioning of metabolism, immune function, mood, and disease resistance functions. Research results gave an indication that a deficiency of sleep, or deprived value of sleep, raises the danger of illnesses counting hypertension, diseases which effect heart, diabetes mellitus, depression, and many more health-related issues.
According to The National Sleep Foundation it is recommended to have a proper night sleep which can be broadly classified into nine age groups as in table 1 (Gais et al., 2002).
Table 1. Recommended night sleep duration for various age groups of human life
| Recommended Night Sleep (hours/day) | Age Group | Life Span |
| 14 to 17 | 0 to 3 months | Newborn |
| 12 to 15 | 4 to 11 months | Infant |
| 11 to 14 | 1 to 2 years | Toddler |
| 10 to 13 | 3 to 5 years | Preschool |
| 9 to 11 | 6 to 13 years | School-age |
| 8 to 10 | 14 to 17 years | Teenage |
| 7 to 9 | 18 to 25 years | Young Adult |
| 7 to 9 | 26 to 64 years | Adult |
| 7 to 8 | 65 or more years | Older Adult |