Tired, Foggy, Achy: Why Poor Sleep Hits Hard (and What To Do About It)

We all know what it feels like to have a bad night (and if you are a parent, a couple of months of bad nights). The collection of symptoms that follows is not just about tired eyes. Poor sleep affects how we perform in the thinking and organisational parts of life, our motivation to make decisions, and even our ability to initiate basic tasks. One of the more common complaints I hear from patients is the extra achiness and pain that show up when they are underslept.

To understand why this happens, it is important to know the systems that govern sleep: sleep pressure and circadian rhythm.

Sleep Pressure and the Glymphatic System

Sleep pressure is the drive to fall asleep. It is associated with that heavy-eyed feeling when you can’t keep yourself awake. Every action you take during the day, thinking, moving, feeling, listening and processing emotions comes with an energy cost. Your brain cells burn glucose for energy, and in the process create byproducts such as adenosine. These byproducts gradually build up in the brain and are monitored by receptors in the hypothalamus. When the levels reach a threshold, your body begins to shift into a tired state.

Once you are asleep, the glymphatic system kicks in. Think of it as a cleaning crew flushing out these metabolic byproducts out of the brain and into the lymphatic system. The ideal window for this clean-up is seven to nine hours, which is why that is the recommended sleep range for adults. When adenosine is cleared, the brain has a fresh start and sleep pressure is reset.

This system is not limited to the brain. Tendons and soft tissues also rely on sleep for recovery. They use the lymphatic system during the night to clear out waste products from activity in a fashion that parallels the glymphatic draining. Therefore, poor sleep disrupts these mechanisms even in tendons. This is one reason why poor sleep can slow healing and why recovery from injury is harder when sleep is disturbed.

Circadian Rhythm and Melatonin

The second system is the circadian rhythm, the roughly 24-hour internal clock that is guided by light and dark. As the sun sets, the pineal gland releases melatonin. This hormone signals to the body that it is night and time to prepare for rest. It lowers core body temperature, reduces blood pressure, dials down alertness signals, and makes the brain more sensitive to the build-up of sleep pressure.

In simple terms, melatonin opens the door and sleep pressure provides the push through it. When both systems are aligned, sleep comes easily. But when they are out of sync—like after a long nap that lowers sleep pressure, a restless night or travel across time zones that disrupts circadian rhythm—falling asleep becomes harder and less restorative.

What To Do After a Bad Night

When sleep is disturbed, the question becomes: how can you restore balance, clear out some of the leftover metabolic byproducts and manage the side effects the next day? Here are the tools I have found most effective.

1. NSDR (Non-Sleep Deep Rest)

The first and most powerful tool is NSDR. This is a guided 10–20 minute practice where you lie down, close your eyes, and follow an audio track into a deeply relaxed state. NSDR lowers heart rate, slows breathing, and shifts the brain into wave patterns similar to early sleep.

It doesn’t fully replace deep sleep, but it provides enough of the cleanout process in the brain to reduce fatigue, sharpen focus, and lower cortisol. NSDR is particularly useful for jet lag, disrupted nights, or simply carrying on after poor rest.

NSDR is a great tool for athletes who have high training volumes or intensities and need the benefits that come from sleep.

Click here for the guided NSDR I use.

2. Manage Light Exposure

Because circadian rhythm is guided by light, managing your environment is key. Keeping your phone in greyscale after 4 pm makes scrolling less appealing and reduces blue light exposure (trust me on this one, it’s a game-changer). Dimming overhead lights in the evening helps mimic the gradual dimming of natural light outdoors, signalling to the body that it is time to wind down.

3. Warm Drinks

A warm, non-caffeinated drink like chamomile tea can put the nervous system into a parasympathetic “rest-and-digest” state. The warmth is soothing and also mimics the heating-cooling cycle of body temperature that naturally happens when sleep begins.

4. Magnesium L-Threonate

Magnesium calms the nervous system by working on GABA receptors, which act as the brain’s brakes. Magnesium L-threonate is unique because it crosses into the brain more effectively than other forms. This helps stabilise brain rhythms, reduce excitatory signals, and regulate melatonin release. It may not always make you fall asleep faster, but it can improve the depth and quality of your sleep.

5. Exercise

Exercise helps counter fatigue in several ways. It boosts blood flow and oxygen delivery to the brain and muscles, increases neurotransmitters like dopamine and norepinephrine, and helps regulate circadian rhythm by encouraging melatonin release later in the day. The other benefit is the deep pressure through the joints (proprioception). This evokes a shift to a more relaxed parasympathic state, which helps restore the energy balance in the brain. Even a light workout can serve as a system reset, improving both alertness in the short term and sleep quality the following night.

Bottom line: A bad night does not have to ruin your day. By understanding the two systems that govern sleep and using tools like NSDR, light management, warm drinks, magnesium, and exercise, you can handle the fog and set yourself up for a better night ahead.