If you’re lying awake wondering why sleep won’t come, you’re far from alone. In 2024, 15.4% of American adults reported trouble falling asleep most days or every day, and another 18.1% had trouble staying asleep. The reasons range from simple habits you can fix tonight to underlying conditions worth investigating. Most of the time, sleeplessness traces back to a handful of common culprits, and understanding which ones apply to you is the first step toward fixing it.
Your Brain’s Stress System May Be Stuck On
The most common reason people can’t sleep is that their body’s stress response won’t quiet down. Your brain produces cortisol, a hormone that keeps you alert and ready to act. In healthy sleep, cortisol drops to its lowest levels during deep sleep. But in people with chronic insomnia, cortisol spikes during nighttime waking periods. The longer you lie awake, the higher your cortisol climbs, which makes it even harder to drift off. It’s a frustrating loop: you can’t sleep because you’re stressed, and not sleeping makes you more stressed.
This doesn’t require a major life crisis. Everyday worry about work, finances, health, or relationships is enough to keep cortisol elevated at night. Even the anxiety about not sleeping itself becomes a trigger. If you’ve ever noticed that the harder you try to fall asleep, the more awake you feel, that’s this cycle in action.
Screens Are Shifting Your Internal Clock
Your body uses light exposure to decide when it’s time to be awake and when it’s time to sleep. Light suppresses melatonin, the hormone that signals your brain to wind down. Even dim light can interfere, as brightness levels around eight lux (roughly twice that of a night light) are enough to affect melatonin production.
Blue light from phones, tablets, and laptops is especially disruptive. In a Harvard experiment, 6.5 hours of blue light exposure suppressed melatonin for about twice as long as green light of the same brightness and shifted the body’s internal clock by 3 hours compared to 1.5 hours for green light. So scrolling through your phone in bed isn’t just a distraction. It’s actively telling your brain that it’s still daytime. If you’re using screens within an hour or two of bedtime, that alone could explain why you’re staring at the ceiling.
Caffeine Lasts Longer Than You Think
Caffeine has a half-life of five to six hours. That means if you drink a cup of coffee at 3 p.m., roughly half the caffeine is still circulating in your bloodstream at 9 p.m. The other half doesn’t vanish either; it takes several more hours to fully clear. Caffeine disrupts deep, restorative sleep and makes it harder to fall asleep in the first place, which reduces your total sleep time even if you don’t feel wide awake.
The tricky part is that people vary in how quickly they metabolize caffeine. Some can drink espresso after dinner and sleep fine. Others are sensitive enough that an afternoon tea throws off their night. If you’re struggling to sleep and consuming caffeine after noon, cutting it off earlier is one of the simplest experiments you can try.
Your Bedroom Might Be Working Against You
Temperature plays a bigger role in sleep quality than most people realize. Your body needs to drop its core temperature slightly to initiate sleep, and a warm room makes that harder. The ideal bedroom temperature for adults falls between 60 and 67°F (15 to 19°C). For babies and toddlers, it’s slightly warmer at 65 to 70°F. If your room regularly sits above this range, especially in summer or with poor ventilation, your body may be physically struggling to cool down enough to fall asleep.
Noise and light matter too. Even if you fall asleep with the TV on or a streetlight shining through thin curtains, these stimuli can prevent you from reaching the deeper stages of sleep, leaving you feeling unrested even after a full night in bed.
Medical Conditions That Disrupt Sleep
Sometimes the problem isn’t habits or stress but an underlying condition. Two of the most common sleep disruptors are sleep apnea and restless legs syndrome.
Sleep apnea causes your breathing to pause, sometimes accompanied by snoring, snorting, gasping, or choking during the night. Many people don’t realize it’s happening because they’re asleep when it occurs. The clearest daytime sign is feeling extremely sleepy despite what seemed like enough hours in bed, or a partner reporting that your breathing sounds unusual.
Restless legs syndrome (RLS) creates a powerful urge to move your legs when you’re lying down or sitting still. People describe it as a creeping, crawling, tingling, or burning sensation. Moving your legs provides brief relief, but the feeling returns. Most people with RLS also experience involuntary leg twitching or jerking during sleep, which fragments rest without full awareness. RLS makes both falling asleep and staying asleep significantly harder.
When Sleeplessness Becomes Insomnia
Everyone has bad nights. The clinical threshold for insomnia disorder is difficulty falling asleep, staying asleep, or waking too early, happening three or more nights per week for three months or longer, despite having adequate opportunity to sleep. It also has to cause noticeable distress or affect your daily functioning, whether that’s trouble concentrating, mood changes, or daytime fatigue that interferes with work or relationships.
If your sleep problems haven’t reached that frequency or duration, they may still be worth addressing, but they’re more likely tied to a specific trigger you can identify and change. If they have crossed that line, effective treatment exists.
What Actually Fixes It
The gold standard treatment for chronic insomnia isn’t medication. It’s a structured approach called Cognitive Behavioral Therapy for Insomnia, or CBT-I. Research shows that 7 to 8 out of 10 people see significant improvement, and unlike sleep medications (which are typically only meant for short-term use), the benefits last long after treatment ends.
CBT-I works through several components. Stimulus control means retraining your brain to associate your bed with sleep rather than wakefulness, so you stop doing things like watching TV, scrolling, or reading in bed. Sleep restriction temporarily limits your time in bed to build stronger sleep pressure, then gradually increases it as your sleep becomes more consistent. This sounds counterintuitive when you’re already exhausted, but it’s one of the most effective pieces. Cognitive therapy addresses the anxious thoughts about sleep that keep the cycle going, like dreading bedtime or catastrophizing about how tomorrow will go if you don’t fall asleep soon.
CBT-I is available through therapists, sleep clinics, and increasingly through digital programs. It typically runs four to eight sessions.
Changes You Can Make Tonight
While long-term solutions like CBT-I take time, a few adjustments can make an immediate difference. Stop using screens at least 30 to 60 minutes before bed, or at minimum switch devices to a warm-light mode. Cut caffeine by early afternoon. Cool your bedroom to 60 to 67°F if possible. Keep a consistent wake time, even on weekends, because your internal clock anchors more reliably to when you get up than when you go to bed.
If you’ve been lying awake for more than 20 minutes, get out of bed and do something quiet in dim light until you feel sleepy again. Staying in bed while frustrated trains your brain to associate the bed with wakefulness. Adults need 7 to 9 hours of sleep per night (7 to 8 for those over 65), so make sure you’re giving yourself enough of a window to actually get those hours.
If you regularly feel excessively sleepy during the day, fall asleep at inappropriate times like while driving, or your breathing sounds unusual during sleep (snoring, gasping, pausing), those patterns point to something beyond simple sleep hygiene and are worth bringing up with a doctor.