Khushi Jain , Bhumi Sharma ‘Sleep Deprivation’ or Insufficient sleep to meet an individual’s physiological and psychological needs is getting more common day by day due to lifestyle changes, work schedules and even health-related concerns. Many people, motivated by the need to be the best , prioritize their work, social meetings and activities, or even their screen time over sleep, leading to a delay in melatonin production which in turn disrupts their biological clock and sleep-wake cycles. Without proper sleep, individuals can show a significant decline in various areas of cognitive abilities like alertness, vigilance, attention and concentration. Evidence also suggests that sleep deprivation can also affect higher order cognitive processes, such as problem solving and decision making, as many of these higher order capabilities are believed to be moderated by the prefrontal cortex, which is supposed to be affected by prolonged sleep disturbance. The Link Between Repetitive Negative Thinking and Sleep Disturbances Consistent with prominent theories of psychopathology, research has reliably shown repetitive negative thinking (RNT) to be a central characteristic of many psychiatric conditions (Beck & Clark, 1988; Borkovec, Alcaine, & Behar, 2004; Rachman, 1997)(Stewart et al., 2018). RNT can manifest in many ways including worry, rumination, and obsessing, but has the shared feature that it is exhibited as frequent negative thoughts that are difficult to control (Ehring & Watkins, 2008). In addition to being characterized by elevated RNT, many psychiatric disorders are also characterized by disruptions in the duration and timing of sleep (Apa, 2013; Boivin, 2000; Harvey, 2008, 2011; Wulff, Gatti, Wettstein, & Foster, 2010)(Stewart et al., 2018). Harvey, Murray, Chandler, and Soehner (2011) argue that sleep disturbance should be viewed as a transdiagnostic process, as it is a feature of most psychiatric conditions. For example, sleep disruptions are reported by up to 90% of those experiencing an acute depressive episode (Wulff et al., 2010) (Stewart et al., 2018). A number of studies document a relationship between Repetitive Negative Thinking (RNT) and reductions in sleep duration or quality (Fairholme et al. 2013; Guastella and Moulds 2007; Harvey 2002; Thomsen et al. 2003; Zoccola et al. 2009) (Nota & Coles, 2014). For example, sleep deprivation has been linked to increased rumination and decreased mood (Baglioni et al. 2010; Pilcher and Huffcutt 1996; Walker 2009) (Nota & Coles, 2014). However, there is still more to be learned about the relation between RNT and sleep duration. Experimental studies that induce rumination or worry prior to sleep have been shown to reduce sleep quality (Gross and Borkovec 1982; Vandekerckhove et al. 2012) and naturally occurring levels of RNT have been shown to prospectively predict sleep quality (Takano et al. 2012) (Nota & Coles, 2014). The Link Between Social Isolation, Loneliness, and Sleep Disturbances A large number of older people encounter both objective and subjective types of social isolation and sleep disorders. Social isolation increases a person’s risk of a wide range of adverse health outcomes and premature death. Social isolation can cause poor sleep quality that has been proposed as one of the possible mechanisms by which social isolation affects people’s health and quality of life. (Azizi-Zeinalhajlou et al., 2022) Another similar factor is loneliness, which can be defined as the feeling of being separate from others, and has been identified as one key aspect of social factors that influence health (Cacioppo and Hawkley (2003) proposed that sleep disturbance is a mechanism through which loneliness influences health, citing two studies led by (Cacioppo (2002a, 2002b) in which lonely persons reported lower sleep quality and showed lower sleep efficiency and higher levels of wake time after sleep onset than non-lonely persons. Therefore, it is essential to comprehend these issues and address them through various treatment plans. The Impact of Sleep Deprivation on Psychological Functioning Sleep deprivation or insufficient sleep is very intricately connected to negative thinking. As we know, lack of rest and proper sleep makes the brain more volatile and more susceptible to emotional reactions and distressing thoughts and feelings. When the brain does not get enough sleep, the prefrontal cortex, which oversees rational thinking, weakens, whereas the amygdala, responsible for processing emotions, becomes increasingly reactive. These imbalances cause a lot of irregularities in an individual, such as frequent mood swings, increasing anxiety as well as ruminating or over-fixating on a problem. Chronic sleep deprivation plays a role in escalating mild symptoms of disorders like anxiety and depression but it also majorly increases the risk of developing serious mental health conditions and disorders. Prolonged sleep deprivation disrupts the brain’s neural pathways, especially those involved in emotional regulation and stress response, which reduces the brain’s ability to recover from emotional strain and cope with daily stressors. Over time, this disruption can have lasting psychological effects, as the brain’s resilience against stress weakens, making it more susceptible to mood disturbances and mental health disorders (Jansen & Narayan, 2024). There is sufficient evidence to show the relationship between sleep disturbance and negative thinking. Sleep is an important factor to consider in developmental psychopathology (Meltzer, 2016). In adults, higher levels of RNT are associated with longer sleep onset latency and poorer sleep quality (Guastella & Moulds, 2007; Nota & Coles, 2015; Zoccola, Dickerson, & Lam, 2009). Further, an initial study in adults that incorporated both sleep duration and sleep timing components in one study found that sleep timing uniquely impacted RNT. Specifically, delayed sleep timing was associated with higher levels of RNT (Nota & Coles, 2015). This can have a serious effect on a person’s mental, emotional and physical well-being. Studies have shown that prolonged insufficient sleep can reduce the size of the hippocampus, which deals with memory and emotional regulation, making one more susceptible towards mental health conditions like anxiety and depression. Due to sleep deprivation, the brain loses its ability to regulate emotions and process information which leads to heightened stress responses and difficulty in concentrating. It can also tamper with the production of neurotransmitters like serotonin and dopamine, which plays an important role in stabilizing mood. This can cause