There’s a certain magic to New Year’s Eve – late-night parties, countdowns with friends, and the excitement of celebrating a fresh start. But while pulling an all-nighter to ring in the new year can be fun and memorable, staying up all night can play tricks on your body. Sleep is a foundational biological process that supports recovery, cognition, mood regulation, and even immunity. When we disrupt that process with late nights and holiday excess, our bodies and brains respond in ways that can leave us feeling anything but celebratory.
From a cognitive standpoint, staying up all night significantly impairs mental performance. Research shows that sleep deprivation increases subjective sleepiness and slows reaction times, diminishes sustained attention, and weakens working memory and decision-making abilities. In some cases, the effects on attention and reaction can be comparable to the impairment seen with alcohol intoxication, making everyday tasks – from driving to work to engaging in conversation – more challenging and even unsafe (1).
Emotionally, the lack of sleep that comes with an all-nighter can heighten negative moods and blunt positive emotions. Sleep loss is linked with greater irritability, anxiety, and difficulty regulating emotions, as well as a reduction in feelings of joy and contentment – ironically, just when social celebrations are in full swing. These shifts occur because key neural circuits involved in emotional regulation are disrupted when sleep is skipped, increasing the likelihood of mood swings and lowered stress tolerance in the hours and days after the event (2), (3).
Physically, staying awake all night affects more than just how we feel – it influences core biological systems, like metabolism and memory. It can also disrupt hormone regulation, weaken immune responses, and elevate stress markers, which may make you feel lethargic, more sensitive to pain or stress, and more susceptible to illness in the days following the celebration (4).
While missing one night’s sleep during New Year’s Eve is unlikely to cause long-term harm for most healthy adults, being mindful of these effects can help you plan recovery sleep and rest in the days around the holiday so you can start the year feeling your best.
(1) Wüst LN, Capdevila NC, Lane LT, Reichert CF, Lasauskaite R. Impact of one night of sleep restriction on sleepiness and cognitive function: A systematic review and meta-analysis. Sleep Med Rev. 2024;76:101940. doi:10.1016/j.smrv.2024.101940. https://pubmed.ncbi.nlm.nih.gov/38759474/
(2) Barnett KJ, Cooper NJ. The effects of a poor night sleep on mood, cognitive, autonomic and electrophysiological measures. J Integr Neurosci. 2008;7(3):405-420. doi:10.1142/s0219635208001903. https://pubmed.ncbi.nlm.nih.gov/18988299/
(3) Tomaso CC, Johnson AB, Nelson TD. The effect of sleep deprivation and restriction on mood, emotion, and emotion regulation: three meta-analyses in one. Sleep. 2021;44(6):zsaa289. doi:10.1093/sleep/zsaa289. https://pubmed.ncbi.nlm.nih.gov/33367799/
(4) Effects of sleep deprivation. Harvard Health Publishing. Published July 23, 2025. https://www.health.harvard.edu/staying-healthy/effects-of-sleep-deprivation