Is there any Sleep limit for a human body? Can we sleep throughout our whole life if we are supplied the necessary things like food,water etc.
Q: Is there any Sleep limit for a human body?
Can we sleep throughout our whole life if we are supplied the necessary things like food,water etc. 

A: Yes, there is a sleep limit for human (and other animals that sleep). And, no, we can’t sleep throughout our whole life even if all our metabolic requirements are supported. This is because sleep does not occur freely without any control but is under control of a complex neural network. This network limits how long one can sleep or be awake. It also regulates the time when sleep is to begin and to end. (Ref 1 - 4)

Sleep occurs alternately with wake in cycles, called sleep-wake cycle. These cycles are under control of a complex network of neural circuits in the brainstem, hypothalamus, basal ganglia, basal forebrain, and thalamus (see figure below).



(The figure is from Figure 2, Ref 1.)

And the periodicity of the cycles are controlled by circadian rhythm pacemaker in suprachiasmatic nucleus, internal homeostasis, and ambient light. (see figure below)



(This figure is from Figure 3, Ref 1)

In human and animals that sleep, this cycle is about 24 hours, with the mean duration of sleep (in human) of about 7.5 hours (with a standard deviation of about 1.25 hours) (Ref 2.). So, normally we sleep about 7.5 hours and then are set to be awake by these neural mechanisms. Because sleep is under control of these neural circuits, we cannot just fall asleep whenever we want and cannot sleep as many hours as we would like.

References:


Larson-Prior, Linda &amp; Ju, Yo-El &amp; Galvin, James. (2014). Cortical–Subcortical Interactions in Hypersomnia Disorders: Mechanisms Underlying Cognitive and Behavioral Aspects of the Sleep–Wake Cycle. Frontiers in neurology. 5. 165. 10.3389/fneur.2014.00165.
Purves D.  Chapter 27 Sleep and Wakefulness. Purves D, Augustine GJ, David Fitzpatrick D, Hall WC, Lamantia AS,‎ McNamara JO, Williams SM, editors. Neuroscience. 3rd ed. Sunderland, Massachusetts: Sinauer Associates Inc; 2004. ISBN-13: 9780878937257 ISBN-10: 0878937250. p659-686.
Moore RY. Clinical Update - Circadian Rhythms, Hypothalamus, and Regulation of the Sleep-Wake Cycle. Medscape. 2019 Sep 1.
Wikipedia. Sleep