Maze Basics: Sleep Fragmentation Chambers

Sleep is essential for our body and mind to recharge, keeping the body healthy and alleviating diseases. Having a good night’s sleep increases our energy and productivity during the day.

Then what happens when we can’t sleep when we are sleep deprived? The list is long! Some potential problems associated with chronic sleep deprivation are high blood pressure, diabetes, heart attack, heart failure, or stroke.

Other potential issues include obesity, depression, reduced immune system function, and lower sex drive. Thus, sleep is crucial for maintaining a healthy body, mind, and brain.

We established that sleep is crucial for our body; what if we started having short interruptions in our sleep? Having repeated brief sleep interruptions during the night is described as sleep fragmentation^[1]. Sleep fragmentation essentially leads to excessive tiredness during the day.

If we want to understand how heavy sleep fragmentation influences our life, some scientific output might help us. Sleep fragmentation might increase the risk for obesity, glucose intolerance, diabetes^[2], and chronic diseases associated with inflammation^[3].

Moreover, sleep fragmentation might also impair our learning and memory process^[4]. As the effects of sleep fragmentation are serious, it is essential to investigate this sleep problem thoroughly.

Here we will introduce sleep fragmentation chambers that you can use in your sleep deprivation studies in mice and rats—interested in sleep deprivation research in rodents? Check out sleeping behavior in mice and group sleeping articles.

Sleep fragmentation chambers are useful tools for observing the detrimental effects of sleep deprivation in lab settings. They aim to awake the animals at precise intervals during the experiment.

Sleep fragmentation chambers used in sleep research may differ based on the difference in their protocols and methods. The protocols are shaped according to which sleep stage the animals will be awakened. Procedures might vary depending on the material used to awake the animals and the study protocol.

Villafuerte and his colleagues (2015) have categorized two types of sleep fragmentation chambers’ protocols in their comprehensive meta-analysis research^[5]. One of them, paradoxical sleep deprivation protocols, is related to sleep deprivation during the rapid eye movement stage (REM).

The other one, total sleep deprivation protocols, is related to sleep deprivation during the non-rapid eye movement sleep (slow-wave sleep). Paradoxical sleep deprivation protocols include three different methods.

1. Multiple small platforms (MSP): In this method, multiple small platforms (3–5 cm) are placed in a tank (40 x 30 cm), which is filled with water. Water covers 1–4 cm of the upper surface of the platforms and is spaced 7 cm. Thus, the animals wake by touching the water (with muscle tone loss).
2. Classical platform (CP): A platform is located in 4.5 – 10 cm diameter containers filled with water up to 1 cm below the platform surface in these chambers. The animals are placed on this platform individually. Hence, they fall from this platform and wake (with a loss of muscle tone).
3. Grid over water (GOW): In these types of chambers, there is a grid floor (29 × 15 × 7 cm) inside the plastic cage, which is filled with water until 1 cm below the grid surface. The animals are placed on this grid floor. The steel rods of the grid are stainless, 3 mm wide. These rods are also located 2 cm apart from each other. The animals awake by touching this water (losing muscle tone).
4. Sleep Deprivation Chamber: Sleep Deprivation Chamber has a cylindrical cage and an automated rotating bar. The bar touches the animals’ feet by rotating frequently. The bar’s rotation and speed can be altered by a screen in the chamber depending on experimental needs. Thus, this chamber keeps the animals awake at researcher-programmed intervals to prevent REM sleep. It also has food and water apparatuses to allow long-term experimentation.

Total sleep deprivation protocols might contain two different methods.

1. Handling: Experimenters use some methods to awake the animals in these chamber types. These methods include gently touching their tails or whiskers, brushing their fur, shaking their cages, or disturbing their bedding in the chamber. Thus, the animals cannot continue to sleep in this condition.
2. Disc over water (DOW): Two rectangular clear plastic chambers are placed side by side in this method. The animals are carried with a single plastic disc (40 cm diameter) built below the two chambers. There is also a rectangular tray filled with water to a depth of 5 cm and extends to the chamber walls under this plastic disc. Once sleep is detected (with an EEG recorder or spontaneously), the plastic disc is run and the animals are awakened by an electric motor.

Trammell, Verhulst, and Toth (2014) studied the health impact and underlying pathophysiological mechanisms due to sleep disruptions. The male mice were used in the study.

For this purpose, they developed and characterized a method that includes a disc that rotates slowly in a random direction for 8 s of every 30-s interval. When this 8 s rotation (180°) occurred, mice contacted the chamber’s wall and woke up.

Mice were randomly assigned to one of the three groups as exposed to 3 different durations of the sleep fragmentation (for 6, 12, and 24 hours). Researchers found that all groups recovered from REM sleep but did not slow-wave sleep.

Dumaine and Ashley (2015) studied how high or low sleep fragmentation levels affect changes in pro-inflammatory and anti-inflammatory cytokine gene expression in the periphery and brain.

The male mice were placed in an automated sleep fragmentation chamber (Lafayette Instrument Company; Lafayette, IN; model 80390) with a swiping bar.

This bar moved every 20 s (high sleep fragmentation group) or 120 s (low sleep fragmentation group) and woke the mice up. Researchers found that some cytokine gene expressions were altered depending on the sleep fragmentation level^[2].

Another research that used a sleep fragmentation chamber was carried out by Razizadeh and his colleagues (2019). Researchers investigated the effect of voluntary exercise combined with sleep fragmentation on spatial learning and memory. They used the Multiple Small Platforms Method (MSP) for sleep fragmentation.

The intact female Wistar rats were used in the study. A running wheel was placed in the rat’s home cages, and the number of revolutions was recorded. After the last exercise, the sleep fragmentation process was started. It has been found that sleep fragmentation has a negative impact on spatial learning and memory.

However, the rats in the sleep fragmentation combined with voluntary exercise condition were better than the rats in the sleep fragmentation with no exercise condition. Yet, they could not reach the baseline status within the learning and memory process^[4].

Scientific debate aside, every aspect of waking life becomes more effortful, labored, and emotionally less fulfilling without adequate sleep. When deprived of sufficient sleep, most of us feel sleepy and physically drained, our mood is noticeably flattened and our thinking feels sluggish and unfocused.

Sleep fragmentation chambers are helpful tools to assess the adverse effects of sleep disruption in laboratory settings. Using these chambers provides crucial outputs such as adverse effects of sleep deprivation on the physical and psychological processes.

1. Smurra, M. V., et al. (2001). Sleep fragmentation: comparison of two definitions of short arousals during sleep in OSAS patients. European Respiratory Journal, 17(4), 723-727.
2. Dumaine, J. E., & Ashley, N. T. (2015). Acute sleep fragmentation induces tissue-specific changes in cytokine gene expression and increases serum corticosterone concentration. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 308(12), R1062-R1069.
3. Trammell, R. A., et al. (2014). Effects of sleep fragmentation on sleep and markers of inflammation in mice. Comparative medicine, 64(1), 13-24.
4. Rajizadeh, M. A., et al. (2020). Voluntary exercise modulates learning & memory and synaptic plasticity impairments in sleep-deprived female rats. Brain Research, 1729, 146598.
5. Villafuerte, G., et als. (2015). Sleep deprivation and oxidative stress in animal models: a systematic review. Oxidative medicine and cellular longevity, 2015.